Picosecond spectroscopy on benzophenone (BP)-triethylamine (TEA) system was performed for the study of the elementary process of hydrogen abstraction by BP in the lowest excited triplet state (³BP∗). TEA was used as solvent since (i) it did not form a ground state complex with ³BP (ii) the rate of hydrogen abstraction was not controlled by the diffusion of hydrogen donor in solvent, and (iii) charge transfer from TEA to BP in the excited singlet state (¹BP∗) was inefficient because the polarity of TEA was lower than that of acetonitrile.
An excitation light source was a second harmonic of a mode-locked ruby lase r (347 mm, 30 ps). Time-resolved spectra and kinetics of the transient absorption were measured with an OMA dual spectrum mode apparatus and with an echelon system, respectively.
The absorption spectrum of ³BP∗ was measured at 0 ps (Fig.4). The lifetime of ³BP∗ was determined to be 50 ps (Fig.7). Ketyl radical was completely formed within 150 ps (Fig.6). Anion radical of BP was not observed. There are two interpretations: (i) the rapid proton transfer from TEA+ to the anion radical of BP or (ii) the direct hydrogen transfer (both electron and proton).³BP∗ abstracts hydrogen from TEA (in less polar media) with the time constant of 50 ps.

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The present paper is concerned with cw CO₂ laser assisted Chemical Vapor Deposition (CVD)of silane molecules (SiH₄). The observed dependence of deposition rates on laser wavelengths indicates that gas phase reactions are involved in deposition processes. We applied a powerful new diagnostic means, Coherent Anti-Stokes Raman Spectroscopy (CARS), in order to detect species involved in the reactions. Temperature was deduced from CARS spectra of N₂ mixed with SiH₄ gas. The CO₂ laser beams were found to raise the temperature of the gas containin SiH₄ when they were tuned to absorption lines of SiH₄. CARS spectra of the heated Sill, gas were characterized by a complicated profile with a broad shoulder and double peaks. We interpreted the shape of the spectra as arising from reaction products, probably Si₂H₆ and hot bands of SiH₄. Applying this interpretation to observed results, we can judge how Siff, molecules are disturbed differently according to laser wavelength and a distance from a substrate. Near the substrate the spectra are characterized by the presence of the broad extra peak of hot SiH₄ and Si₂H₆ in addition to the main peak of SiH₄. As the distance from the substrate increase, the extra peak gets close to the main peak and the widths decrease. This suggests that the effect of substrate on heating the molecules in the gas phase is very efficient when the cw CO₂ laser beam is normal to the substrate.

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Infrared multiple-photon decomposition (IRMPD) of perfluorodimethyl ether, (CF₃)₂O, induced by a pulsed CO₂ laser has been studied as functions of pulse number, laser wavenumber, laser fluence, and reactant pressure. The decomposition gave carbonyl fluoride (54%), carbon monoxide (24%), hexafluoroethane (37%) and carbon tetrafluoride (5%) as main products, and tetrafluoroethylene (<1%) and difluoroacetylene (<1%), where the numbers in parentheses show the product yields relative to the (CF₃)₂O decomposition yie ld. The product distribution and the (CF₃)₂O decomposition yields changed depending on experimental parameters. The observed results are explained on the basis of the unimolecular decomposition of highly vibrationally excited (CF₃)₂O produced in the IRMP absorption process. The overall mechanism involves homolytic cleavage of the C-O bond to form trifluoromethyl and trifluoromethoxyl radicals, subsequent radical-radical reactions, and fragmentation of hot radicals or products.
The ₁₈O separation in the IRMPD of (CF₃)₂O has been extensively studied under various experimental conditions. The measurements of the isotope ₁₈O/₁₆O in CO were carried out using GC-MS system. The separation selectivity showed a maximum value of 2.5 in the irradiation of 3.5 Torr (CF₃)₂O with laser pulses at 940.55 cm^-1 and 15 J. cm^-2, where the conversion was 1.4%. However, the selectivity decreased with increasing pulse number, fluence, and pressure. t IR Photoc hemistry of Organic Compounds. I.

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The ionization and dissociation processes of He⁺+N₂O charge-transfer (CT) reaction have been studied in a flowing afterglow by emission and laser-induced fluorescence spectroscopy. The N₂O+(A²∑⁺-X²∏₁) and N₂⁺+(B²∑u⁺-X²∏g⁺) emission spectra have been identified. The vibrational distribution of N₂O+(A) produced by the He⁺+-FN₂O CT reaction was determined and compared with that produced by the He⁺(2³S)+N₂O Penning ionization which proceeds via a vertical ionization process. The upper limit of the amount of N₂⁺+ ion produced in the B state is estimated to be at most 2% of the total amount of the produced N₂⁺+ ion, which has been obtained by comparing the total emission intensity of N₂⁺+(B-X) with that of N₂O+(A-X). No N₂O⁺(A-X) emission was observed by the He⁺2++N₂O and Ned-N₂OCT reactions, suggesting that the N₂O+(A) state is formed by a cascade from the higher excited electronic state of N₂O⁺. The relative populations in the vibrational levels up to v''=3 were determined by probing the B-X transition. The vibrational distribution of N₂⁺+(X) is inverted, which indicates that dissociation of N₂O+ into the vibrationally excite d N₂⁺+(X) state is an important exit channel for the formation of N₂⁺+ ion in the He⁺+d-N₂O CT reaction.

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UV light from an expanded laser at 193 nm or a low pressure mercury lamp (254 nm +185 nm) was irradiated on the solid composed of CH₃CN and NH₃ at 77∼130 K. Primary photochemical processes were studied by the photodesorption of product molecules on the solid surface. A pulsed laser at 248 nm (∼20 mJ/cm2) was used as a photodesorption light source and the mass numbers and translational energies of the photoproducts were measured by a quadrupole mass spectrometer. Formation of C₂H₂N₂ and C₂H₄ from CH₃CN has been ascribed to a disproportionation reaction of two acetonitrile molecules, which is the main reaction in a pure acetonitrile solid. Aminoacetonitrile (NH₂CH₂CN) and acetamidine (CH₃C(NH₂) =NH) were formed through a bimolecular condensation reaction of CH₃CN and NH₃ and the addition reaction of the two parent molecules, respectively.
The product analysis of the CH₃CN + NH₃ solid irradiated with a low pressure mercury lamp at 77∼130 K was performed by the use of a liquid chromatograph and a high resolution mass spectrometer. As well as the primary products, many large molecules such as DAMN (diaminomaleonitrile), AICN (5-amino-4-imidazolecarbonitrile) and other HCN oligomers, were detected in secondary photoproducts, which are known as precursor molecules in the prebiotic synthesis of purines, amino acids and peptides.

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The carbon-13 separation by infrared multiple-photon decomposition (IRMPD) of CF₃Br, and C₂F₆ and Br₂ mixtures has been studied as functions of various experimental parameters such as irradiation temperature, reactant pressure, and irradiation wavenumber. The irradiation was carried out with a CO₂ TEA laser. The main products in IRMPD of CF₃Br were C₂F₆ and Br₂. Isotope ratios ¹³C/¹²C in C₂F₆ have been determined using a mass spectromet er combined with a gas chromatograph. The selectivity increased with decreasing temperature; for example, the observed values were 75 at 22°C, 230 at -78°C, and 400 at -110°C. Although the selectivity decreased rapidly with increasing pressure, it was almost constant at pressures below 3 Torr. As the irradiation wavenumber was increased from 1035 to 1055cm-1, the selectivity decreased and the yield of C₂F₆ increased. However, the ¹³C yield was found to be relatively constant in the region of 1040-1050 cm^-1. Taking the wavenumber dependences of the selectivity and the ¹³C yield into consideration, we conclude that the optimum irradiation wavenumber is in the vicinity of 1040 cm^-1. The IRMPD of C₂F₆ and Br₂ mixtures gave CF₃Br as a main product. Carbon-13 was considerably enriched in the product in the irradiation with laser lines at wavenumbers above 1070 cm^-1. The maximal selectivity in the present experiment was 35 at the laser fluence of about 2 J⋅cm^-1, the wavenumber of 1083.5 cm^-1, and 22°C. Since being able to produce CF ₃Br enriched in ¹³C, the IRMPD of C₂F₆ and Br₂ may be used for the production of ¹³C with a high purity.

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The infrared spectra of 2-chloroethanol and 2-chloroethylamine have been studied in lowtemperature matrices. In the case of, 2-chloroethanol, the spectral changes in the C-Cl stretching and 0-H _stretching regions indicated that the gauche to trans isomerization around the C-C bond occurred by infrared irradiation (Fig.1). These spectral changes occurred in the argon matrix but not in the nitrogen matrix. When the nozzle temperature was elevated from room temperature to 750 K, the populations of the trans conform ers increa, sed in both argon (Fig.2) and nitrogen (Fig.3) matrices. However, the relative intensities of the resultant trans conformers in the nitrogen matrix were different from thos e in the argon matrix.
In the case of 2-chloroethylamine, the spectral changes in the NH₂ wagging and C-Cl stretching regions indicated the gauche to trans isomerization around. the C-C bond in argon matrices (Fig.5 and Fig.6). The spectrum of the resultant trans form changed by elevating the matrix temperature from 20 to 28 K. The rate of this transformation strongly depended on the matrix temperature (Fig.7). The same result was obtained in the deuterioamino species, ClCH₂CH₂NHD and ClCH₂CH₂ND₂ ( Fig.8).

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In the present work, multiphoton ionization (MPI) experiments with one- and two-color lasers were carried out mainly for NO molecule in the gas phase to study dynamic behavior of its highly excited states including super-excited states. Molecules of NO were excited to specific vibrational levels (v'=0 or 4) of Rydberg A and C states. In the ionization experiments, we have initially measured ion-current spectra as a function of laser wavelength, and then obtained photoelectron spectra at several ion-current peaks which correspond to specific vibrational (and rotational) levels of the Rydberg states. In direct (1+1) and (2+1)resonant ionization of NO through the Rydberg A and C states, we have obtained single photoelectron peaks due to Δv=0 ionization transitions. However, when NO is further excited to higher Rydberg states from the C state, we have obtained the photoelectron spectra for the first time which are due to autoionization from specific vibrational levels of super-excited Rydberg states. It is emphasized that the present work presents several typical important examples for studying dynamic behavior of higher excited states of molecules in the gas phase.

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Fine and uniform SiC(β-form) powders were synthesized by CO₂ laser driven gas phase reactions of Sill, and C₂H₄. The powders were characterized with emphasis on the compositions and particle size. The chemical composition varied with the ratio of [C₂H₄]/[SiH₄] and with reaction temperatures. The particle size was in the range of 17.0 nm to 48.5 nm, and it increased with increasing laser intensity and partial pressure of B-doped SiC powders were also synthesized.

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A detailed discussion is directed to discharge methods which have generated about 40short-lived molecules and free radicals consisting of two to six atoms. Special attention is given to the development of generation methods that are particularly suitable for spectro-. scopic methods capable of unambiguously identifying short-lived species. Two types of the discharge methods are employed: in one of them active species like atomic fluorine and oxygen are produced outside a cell and react with other materials including those in the solid state inside the cell and the second method induces reactions directly in the cell by a discharge in a mixture consisting of two or more reactants. Advantages and disadvantages of the two methods are compared. An excimer laser photolysis is discussed as a method of generating short-lived molecules, placing a special emphasis on information obtainable on initial process of photolysis. Several sulfur- and phosphorus-containing molecules are discussed as examples of short-lived species, including their generation and reactions.

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Liquid ionization mass spectrometry developed for ionizing a liquid sample at atmospheric pressure is described as a chemical laboratory. One of advantages of the method is easy sample handling. In general, an intense MH⁺ peak of an organic compound is observed and makes it easy to determine molecular weight of the compound. A CAD (collisionally activated dissociation) spectrum measured at an optimum temperature for obtaining MH+ as the base peak shows fragment ions due to the loss of a neutral molecule from the MH+ and the simple cleavages of the MH+ ions, which are characteristic of the structure of the compound (Figs.2∼7). Information on dissociation energies of various bonds in a molecule may be obtained from CAD spectra measured at several different pinhole voltages (Vp) which are related to the ion energies (Fig.3).
Mass spectra obtained at several dif ferent temperatures of a sample give information about the thermal properties, such as stability, melting point and decomposition scheme, and the structure of the compound (Fig.4). The use of additives (matrix, solvent and reagent) is very important to obtain a reproducible mass spectrum, to understand interaction between molecules, and to measure proton affinities of compounds involved. When a mass spectrum is measured, a reagent (R) like hydrazine is introduced into the ion source and produces the adduct ions (MH⁺R) which provide information about positions of functional groups, that is useful to distinguish geometrical isomers (Figs.6 and 7). Use of a labelled compound like D₂O gives information about H-D exchange reactions and the number of active hydrogens (Fig.8).
We can obtain several different mass spectra for one compound in a short period of time by using several reagents. Systematic studies on properties of compounds by the method should be done not only for analytical purpose but also for other fields of chemistry.

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When the plasma polymerization of tetrafluoroethylene was applied to coating of powders such as Porapak Q and silica gel having spherical and complex surface structure, respectively, vibrational mixing of the sample powder during the coating process was essential to ensure entirely uniform coating layer all around the particles. Coating of the same materials under stationary conditions resulted in nonuniform or imperfect coating layer in spite of the use of highly diffusible plasma gas under low pressure. While our previous experiments revealed that the coating layer was susceptible to gas permeation of small molecules suggesting the distribution of micropores within the polymer matrix, a further attempt was made to evidence the micropores by applying high-pressure water onto a film of the polymer. The polymer film thus deposited on porous membrane filter actually conducted water flux, although higher pressure was needed for thicker polymer films. Another experiment was carried out to roughly estimate the pore size by ultrafiltration of organic solutes having different molecular sizes. The pore size was derived to be 20∼40 Å from the exclusion limit. Measurement of the electric conductivity through the polymer film kept in contact with an aqueous electrolyte solution also indicated some permeation of the electrolyte into the polymer film. It was therefore postulated that a small number of radicals might have survived in the plasma polymer and be oxidized by subsequent exposure to the ambient air to form polar functional groups. The electrolyte solutions are considered to be transported through the channels of micropores by successive hydration of the polar groups.

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Permeation characteristics of plasma-polymerized pyridine thin films for water-soluble solutes have been investigated. The rate of salt rejection in reverse osmosis tests was found to be independent of the concentration of the salt solutions while marked decline in water flux was observed with increasing concentration, when the applied pressure was kept constant. The decline of the water flux was attributed mainly to raised osmotic pressure of the sample solution but also to concentration polarization in the vicinity of the filter surface even under the efficient stirring of the salt solution. The polymer film also performed the function of ultrafiltration of organic solutes having various molecular sizes in aqueous media. An approximately 10 Å pore size was derived from the exclusion limit. For smaller organic molecules than the exclusion limit, reverse osmosis separation was again effective if the molecules were ionized in acidic or alkaline media. Concentration of solutions either by reverse osmosis or ultrafiltration using a small filter area was as efficient as a laboratory rotary evaporator.

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The influence of the pressure during oxidation treatment of carbon black by low temperature plasma and plasma diagnosis by emission, spectrographic method were studied in order to obtain informations about the mechanism of plasma oxidation. The formation conditions and molecular weight distribution of degradation products formed on the carbon black surface were also investigated. The oxidation reaction hardly proceeded when the sample was treated under low pressure by decreasing the oxygen flow or under air plasma instead of oxygen plasma. However, the pH of sample shifted toward acid side and heat of immersion in water increased and also water dispersibility improved with increasing the pressure by increasing oxygen flow. More than 1.8 Torr pressure was required to make the sample of good dispersibility in water. It was concluded from these results that the plasma oxidation reaction of carbon black preferentially proceeded as radical auto-oxidation reaction between oxygen molecules and radicals formed, on the carbon black surface. A good, correlation was observed between the dispersibility in water and amount of degradation products on the carbon black surface.

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The depostition of silicon nitride film at room temperature using a low frequency (50 Hz)silane (SiH₄)-nitrogen (N₂) mixture plasma CVD was investigated. The refractive index (n) and the resistivity of the film was 2.0 and about 10¹⁵ ohm cm respectively, These v alues were comparable with those of Si₃N₄ grown by thermal CVD process. Silicon nitride films with n =2.0 were obtained at SiH₄ (10%)-N₂ (90%) mixtures at a total pressure of 1.2 Torr with about 1.5 W input power, and the growth rate of the film was 80Å/min. Moreover, it was found that both n and the film thickness ( t) were approximately proportional to the amount of N₂ (k%) in the mixture. The emission spectrum of the low frequency plasma in the SiH₄ -N₂ mixtures was measured with a monochromator in a wavelength range from 2000Å to 8000Å. The emission of emitting excited states of Si, SiH, H, H₂ and N₂ in the SiH₄-N₂ mixture plasma could only be confirmed. The plot of the Si emission intensity against k had a maximum. Moreover, the emission intensity of the 2 nd positive band from N₂ excited molecules increased exponentially with increasing k. These results were discussed from the standpoint of the collision of the excited N₂ molecule and Si atom. No difinite relationship between the Si emission intensity and the properties of the film could be found.

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Nitriding of silicon wafer was carried out in a nitrogen or nitrogen-hydrogen plasma generated by an rf discharge. The specimen of 20×10 cm2 cut from p type (100) oriented CZ wafer of 400μm in thickness was set in the quartz tube and reacted with nitrogen or nitrogenhydrogen plasma. The specimen was set apart from the coil and heated at 800°C with an electric furnace. The pressure and the rf power were maintained at 10 Torr and 300 W, respectively.
When silicon wafer was reacted with nitrogen plasma for specified period up to 8 h, no nitriding was observed and SiO₂ was formed on the surface. The film thickness formed on the silicon wafer fluctuated between 60∼500Å and the refractive index was 1.5∼1.6. When the silicon wafer was reacted with nitrogen-hydrogen plasma up to 8 h, the nitriding was succeeded. The refractive index was 2.0±0.1 and was approximately equal to that of silicon nitride obtained by the chemical vapor deposition. Infrared spectra of films obtained after the nitriding were measured. For the sample obtain-e-d- by nitriding with nitrogenhydrogen plasma, only peaks based on Si-N bonds were observed. The peaks based on Si-0bonds observed in the film obtained with the nitrogen plasma was disappeared.
The kinetics of nitriding of silicon wafer with nitrogen hydrogen plasma varied in course of nitriding. The reaction between the gas phase and the silicon wafer may be the rate determining step in the early stage of the reaction. In the case of longer reaction time, the diffusion of nitrogen may be the rate determining step.
From the plasma diagnostics, N₂ and N, + were identifi ed in the nitrogen plasma and N₂N₂+, NH and H were identified in the nitrogen-hydrogen plasma. When hydrogen w as added into the nitrogen plasma, N₂+ ion was substantially decreased by the formation of nitrogen-hydrogen molecules or molecular ions and the sputtering of SiO₂ by N₂+ was suppressed and the nitriding of silicon was successful.

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Conditions suitable for the selective formation of HCHO in the reaction induced by the silent discharge in H₂-CO mixtures have been studied extensively. Results are summarized as follows.
1. When the flow rate of circulating gas mixture is kept constant, the yield of HCHO increases linearly with the length of discharge tube.
2. When the tube length is fixed, the yield of HCHO (Y) increases according to the empirical rule Y = k logτc, where τ is the residence time of flowing gas in the discharge tube.
3. Maximum yield of HCHO as well as CH₄, which is the second dominant product, is obtained at a gas composition H₂/CO=2.
At the present stage, a space -time yield of 36 mol⋅m^-3. h^-1 has been obtained and a tentimes increase of this figure seems promising.

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A new application of plasma assisted chemical vapor deposition (PCVD) and oxidation processes to fabricate matal-nitride-oxide-amorphous silicon (MNOS) type nonvolatile semiconductor memory devices are presented.
The experiment was intended to explore the possibility of realizing large-area, low-cost semiconductor disk memory, and MNOS nonvolatile memory capacitors have been fabricated. The deposition of amorphous silicon and silicon nitride films and the growth of silicon dioxide film in oxygen plasma were performed in a capacitively coupled rf PCVD equipment in situ.
Amorphous silicon films were deposited using 100% SiH₄ plasma on Corning 7059 gla sses coated with Mo films, which were found to make good ohmic contacts to the amorphous silicon. Silicon nitride films were deposited using the plasma dissociation of mixed gas of SiH₄-N₂. The dilution ratio of SiH₄/N₂ and the rf power were intentionally varied, and th e Si/N ratio, the deposition rate and the resistivity of silicon nitride films were measured to find the optimum deposition conditions. The oxidation conditions were evaluated using the C-V characteristics of MNOS diodes.
The C-V characteristics of MNOS diodes fabricated on the optimum conditions were measured at 1 MHz. Experimental results show sufficiently short write time and long retention time, and comparatively little degradation after write/erase cycles for applying these devices.

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The deposition of flourinated amorphous silicon(a-Si: F: H) films from a plasma including SiF₄ gas, which are expected to surpass hydrogenated amorphous silicon(a-Si: H) films as materials for applications such as in solar cells, is generally difficult as compared with that of a-Si: H films. Therefore, in this paper the plasma parameters and the chemical reactions in an rf (13.56 MHz) SiF₄ plasma were studied for the development of deposition technique. The plasma parameters such as a mean electron energy and an electron energy distribution function were measured by the Langmuir probe method. Optical Emission Spectroscopy(OES) and Mass Spectrometry(MS) were utilized for observing the reactive species in the plasma and also for discussing possible chemical reactions.
Four basic dissociation reactions of SiF₄ molecules by the electr on impact were confirmed by the results of the OES and the MS measurements. In H₂+SiF₄ (50%) plasma under the conditions of pressure; 1.0 Torr, gas flow rate; 1 sccm, and RF power; 28 W, an electron energy was measured to be about 11.2 eV, and from this value the probability of four basic dissociation reactions mentioned above: was1 supported. From a pure SiF₄ plasma the deposition of amorphous silicon films may be impossible because of the dominant etching action of F radicals which came from the dissociation reactions of SiF₄ molecules. The generation of these F radicals could be almost suppressed with the addition of only a little amount of H₂ gas, which was confirmed by the OES. Ttieref ore, for the film formation from a SiF₄ plasma, a following reaction must be quite important,
F+H (or H₂)→HF
From the OES measurements, the acceleration of the dissociation reactions of SiF₄molecules with the addition of H₂ gas was also confirmed.

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In this paper we report two chemical reactions which occur on solid wall surface under the influence of an ECR plasma with low gas pressure (<10^-2Pa).
One reaction is ammonia synthesis by the use of an H₂-N₂ mixture plasma. The system is not in equilibrium state. When the solid wall surface is used as a catalyst, a very high selectivity and also a high yield are obtained. The yield is about 70 times higher than that expected for usual systems in thermodynamically equilibrium state.
Another one is erosion of carbides by a hydrogen plasma. A chemical sputtering of carbon atoms in carbides is found when they are irradiated by a hydrogen plasma. The threshold values in hydrogen ion energy for the chemical sputtering are found to be 130 eV for TiC and 80 eV for SiC. These results show that the glow discharge cleaning gives a change in the composition of the first wall of fusion devices (ion energy∼10² eV), but the ECR discharge cleaning does not (ion energy<10 eV).

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The molecular geometry of GeH₅⁺ has been determined. It is a loose complex of GeH₃⁺and H₂ fragments. The molecular symmetry is C₅, but is not D_3h, proposed by Hartmann et al. The chemical bond of GeH₅⁺ is analyzed in detail with various kinds of technique and from a number of points of view.
The proton affinity of GeH₄ is 7.12 eV. It has been found that the SCF calculation i s sufficient for the absolute value of the proton affinity, since the corrections cancel out to become negligible.
The reason why it is difficult to detect GeH₅⁺ in the proton transfer reaction of GeH₄ has been discussed. Only 0.31 eV is enough to stabilize GeH₅⁺ in reference to GeH₃⁺+H₂. The large amount of energy gained by protonation is distributed among the molecule during relaxation. When the bond between GeH₃⁺ and H₂ gains surplus energy over its bond energy, the bond easily dissociates into fragments.
These results are obtained by the calculation with ab initio LCAO-MO-SCF method using the basis set of double-zeta quality plus a diffuse GTO in each shell. Furthermore, polarization functions are added; f-type for Ge and p-type for H.

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The present paper aims to establish a better understanding of species and their concentrations in an arc plasma and of the topographies of the deposited surface.
A zirconium dioxide plasma was produced by arcing betwee n a hollow cylinder of a sintered zirconium dioxide anode and a tantalum ribbon filament in the center of the anode at vacuum, and the ions inside the plasma were introduced into a mass spectrometer directly. The data from the mass spectrometric analyses were compared with those from calculations of statisticalthermodynamics. The deposition from plasma on a tantalum filament was examined by scanning electron microscopy.
The results sugg est that the collision of energetic particles (in this case, electron) with neutral ones plays an important role to estimate the concentration of ionic species in a plasma and that the values of particle collision processes should be combined with those of thermodynamical calculation to understand the chemical species in a low pressure arc plasma.
Topographies of plasma deposited surface were discussed in comparison with those of glow plasma and vapor depositions.
Characteristic pa ttern of the arc plasma deposition had a waterlily-like shape and the number of the pedals decreased with substrate temperature and duration of arcing, and increased with the plasma current density. It should be noted that the topographies were very similar to those of the sputtered surface published by others.

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This paper reports the formation of diamond particles and films on diamond and nondiamond substrates by means of microwave(2.45 GHz) glow discharge in a stream of the hydrogenmethane mixtures. The dependence of the feature of grown diamond on experimental conditions, such as methane concentration, pressure, substrate temperature, microwave power and gas flow rate, is discussed. Diamond was formed on silicon wafers, silica glasses and natural diamonds under the following conditions: methane concentration, 0.3∼2%; total pressure, 4∼26.6 kPa; microwave power, 150∼500 W. The temperature of the substrate ranged from 800°C to 1000°C, depending on the microwave power and the gas pressure. For identification, the deposits were studied by reflection electron diffraction and Raman spectroscopy. The diffraction pattern of the deposit on a silicon wafer consists of spotty rings. The interlayer spacings are in good agreement with the values reported for diamond(Table 1). A sharp Raman peak observed at 1333±1.5 cm^-1 agrees with the reporte d value of 1332.5 cm^-1 for diamond. The deposits were observed with scanning electron microscopy. The faces that predominantly appeared were {111} or {100} faces. Cubooctahedral, twinned and octahedral crystals, all truncated by the substrate, have been observed. When the methane concentration was constant, polyhedrons were formed at lower microwave powers and irregular shaped crystals were formed at higher powers(Fig.4). At h igher substrate temperatures than 980°C, the size of the deposits became small in comparison with the deposits at 930°C(Fig.4). It seems to be due to the vaporization reactions of the deposits with atomic hydrogen. A polycrystalline diamond film was formed on a mechanicall activated silicon wafer(Fig.5). The Raman spectrum of the film formed at the meth aney concentration of 0.3% and the microwave power of 500 W consists of only a sharp peak at 1333cm^-1 (Fig.6 b). The film is transparent in the infra-red region of 2.5-25μm (Fig.7), It seems that hydrogen atoms in microwave plasma react with carbons of graphitic structure t o vaporize the carbons, and bond to carbons of diamond structure to stabilize the st ructure. Th e decomposition of methane on the substrates may be the rate -controlling step for the diamond synthesis. The growth rate increased with an increase in the substrate temperature. A t higher temperatures than 950°C, apparent growth rate decreased because of the reaction of the deposits with atomic hydrogen.

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Reactions between coals and hydrogen atoms were investigated in a discharge flow apparatus (Fig.1) at temperatures ranging from 130 to 250°C under 133 Pa. Australian coals (Yallourn, Goonyella) and domestic coals (Taiheiyo, Miike) (Table 1) were first heated in helium until dry distillation was substantially completed. The thermally stabilized coals were then irradiated with hydrogen atoms. Rate of the formation of organic components increased by a factor of about 10³ upon the hydrogen atom irradiation (Fig.2).

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Product analysis was carried out for radiation-induced reaction of CO/H, gas mixtures with CO contents between 1∼90% in the presence and absence of silica gel. Low-molecularweight hydrocarbons and CO₂ were produced in good yields from the reaction of the mixtures over the whole range of CO content in the presence of silica gel. The yield of H₂O produced over silica gel, on the other hand, decreased markedly with CO contents higher than 5%, suggesting that silica gel exhibits catalytic activity for the water gas shift reaction under electron beam irradiation. The role of silica gel in the formation of hydrocarbons in the radiation chemical reaction of CO/H₂ mixtures is discussed on the basis of the results obtained from the studies of the radiolysis of CO which produces CO₂ and carbonaceous solid, and the structure and radiation-induced hydrogenolysis of the carbonaceous solid.

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Hydrogenated amorphous silicon-carbon alloy (a-Si_1-xC_x: H) has a wide optical energy gap which can be varied with film composition. This material is promising for light em i tting devices because of intense whity visible photoluminescence at room temperature in the samples with large carbon content x.
In this study, a-Si_1-xC_x: H thin films with large x(0.5<x<0.99) have been prepared successfully by a glow discharge method using mono-silane and ethylene gases at low t(emperatures (room temperature--250°C). The physical properties of a-Si_1-xC_x: H thin film s e. g., deposition rate, film composition, structure, hydrogen content, density) have been characterized by infrared absorption and Auger electron spectroscopy. The plasma conditi o ns have been made clear by optical emission spectroscopy during deposition in order t o re veal the glow discharge deposition mechanisms.
The decomposition of ethylene gas is s u ppressed when the mono -silane gas composition H(%SiH₄=SiH₄/(SiH₄-C₂H₄)) is less than 10% and the deposition rate decrease s rapidly. ydrocarbon (C-Hn, n≥2) amount incorporated into the films increases with decreasing %SiH4. In the films deposited at room temperature, the hydrogen content increase s with x land amounts to 60∼80 atomic percent, which yields small density of 1.2∼1.5 gicm3. The fialrge amount of hydrogen in the films leads to a large optical energy gap of 4.02 eV for the ms of x=0.99. On the other hand, in the films deposited at the high substrate t emperature off 250°C, the hydrogen content is about 40 atomic percent because hydrocarb on i s desorbed rom the substrate surface. The density is about 2.0 g/cm3 and the optical energy gap is smaller than that of the films with the same composition x, deposited at room temperature.1

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Plasma polymerization of methyl methacrylate was performed in a down stream of carrier gas glow discharge. The effects of carrier gases on growth rate and etching rate of the film were studied. IR, ESCA and NMR measurements were carried out for the film and the molecular structure and reaction mechanism were discussed. The films were also delineated by the electron beam and X-ray and served for a plasma etching. Their qualities as a resist were evaluated.
In the case of inert carrier gases, radical reactions were expected to be a predominant mechanism and the molecular structures resembled a conventional polymer. For the carrier of reactive gases like oxygen, ionic reactions were observed and the molecular structures did not resemble the conventional one. In the case of dry etching development, the film as a resist showed higher sensitivity than that of conventional polymer. However, the sensitivity was still low for the practical use.

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The reaction of benzene in a 13.56 MHz glow discharge plasma is described. Major products were the lower molecular weight hydrocarbons such as acetylene and methylacetylene due to the ring cleavage. Biphenyl and polymeric deposit on the reactor wall were the significant by-products. The effects of reaction conditions on the rate were examined, and the reaction scheme involving successive electron collisions was assumed. Thus, the difference in the reactivities of C₆H₆ and C₆D₆ could be explained consistently in terms of the life times of activated species, most likely electronically excited benzenes, formed by the first electron collision. Furthermore, theminor pathway giving rise to biphenyl was discussed, principally on the basis of the isotope effects observed in biphenyl formation in the reactions of C₆H₆ and C₆D₆ mixture, and phenyl cation was presented as one of the most responsible precursors.

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Plasma-initiated emulsion (O/W, W/O) polymerization of various kinds of vinyl and diene monomers was carried out. It was found that emulsified (O/W) isoprene (Ip) could be polymerized easily by the exposure of plasma as short as 60 s, followed by the postpolymerization at 25°C. However, emulsions of monomer such as butadiene, styrene, α-methylstyrene, butyl vinyl ether, isobutyl vinyl ether and vinyl acetate were not susceptible to the polymerization.
The obtained polyisoprene had a molecular weight as large as 1.4×10⁶ g/mol with 35%cis-1, 4-, 55% trans-1, 4-, and 11% 3, 4-microstructure. The active specie generated by this method was of long-lived and therefore, the block-copolymers of Ip with butyl acrylate and methacryl ate were prepared under emulsion conditions. It was also found that water solu ble monomers such as sodium methacryate, 2-hydroxyethyl methacrylate, and acrylamide could be polymerized rapidly, when they were emulsified in toluene or butyl acetate to give water soluble microparticles. Using this technique invertase was encapsulated in the crosslinked microparticles and the activities of immobilized enzymes were measured.

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It was found that inorganic substances such as I₂, K₂Cr₂O₇, and K₃[Fe(CN)₆] were reduced efficiently and quantitatively in DMF when they were exposed to a radio-frequency cold plasma. The reduction was considered to occur by the direct addition of high-energy electrons in the plasma to the inorganic substances to give I₂, Cr⁰, and K₄[Fe(CN)₆], respectively.
The reduction occurred in DMF, but not occurred in water, mthanol and in crystalline state. From the experimental results at various I₂ concentrations and various plasma powers, an apparent rate of reduction of I₂ could be expressed as:
R=K[I₂]-^0.3 [PLASMA PO WER]⁰ It was also found that“postreduction” took place whe n these substances were left standing in vacuo after the plasma exposure.

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“Taiheiyo” coal was thermally decomposed by an argon thermal plasma to release the product gases. Hydrogen gas was added to the plasma flow with the coal particles to get high conversion. Acetylene, methane, hydrogen and a trace of carbon monoxide were found as the product gases. A high selectivity to acetylene was observed experimentally compared with a low selectivity to methane.
A one-dimensional model was us ed to investigate the mechanism of the decomposition and the way to increase the acetylene selectivity or conversion. We assumed ( a ) the rate determining step in the heat transfer which causes a uniform temperature of coal particles and ( b ) a fixed decomposition temperature. The addition of hydrogen causes ( 1 ) the rapid increase of temperature on the coal particle and ( 2 ) the rapid drop of temperature in plasma flow because of the increase in the thermal conductivity of the H₂-added plasma. The first means the short induction period prior to the decomposition, i. e. a large conversion, and the second means the small heat flow, i. e. a small conversion. These two factors have the same order influences, but the second has another aspect simultaneously, i. e. a long resident time in reaction zone, and this cancels the decreasing effect on the heat flow. The conversion increases with increasing the hydrogen gas amount mainly by the first reason.
The addition of gas to a plasma flow reduces the initial plasma temperat ure. The addition of argon gas was experimentally examined instead of hydrogen gas, and the conversion only decreases.

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Plasma chemical reactions produce microcrystalline states of silicon and germanium (μc-Si and μc-Ge), Atomic and morphological structures of μc-Si grain and film are investigated by means of electron microscopy, vibrational spectroscopy, etc.
The grain of, μc-Si produced by rf sputtering of a Si dis k target in pure H₂ atmosphere (Table 1) consists of a single crystal of Si (diamond structure) in irregular shape of dimensions 5∼50 nm (Fig.1 and Fig.2). The surface of μc-Si grain is covered with hydrogen atoms covalently bonding with Si atoms (Table 3). Content of hydrogen in, uc-Si film has been measured to be about 30 atom%.
A film of μc-Si shows colum nar structure composed of the aggregate of μc-Si grains, when the film is sufficiently thick. The columnar structure develops with the growth of μc-Si film (Fig.3 b). The surface morphological observation of the film by SEM shows roun d grains in shape with dimension of several hundred nm (Fig.3 a).
Crystalline nature of μc-Ge is summarized in Table 2.
Optical absorption spectra of μc-Si and, uc-Ge resemble those in the single crystal Counter parts (Fig.6 and Fig.8). Photoluminescence spectra of μc-Si film show also crystalline nature rather than amorphous one (Fig.7). There are many defects including ESR centers of ∼10¹⁸ spin/cm3 in μc-Si grain and film.
Infrared absorption bands in Si-H stretc hing vibration region- are composed of sever al fine peaks (Fig.4). Assignment of these peaks is discussed in terms of electron negativities of adjacent substituted groups, symmetric and anti-symmetric vibrations of SiH₂ group, and SiH structures located closely each other on ac-Si grain surfaces.
A morphological model for μc-Si film produced by rf glow discharge decompositio n of SiH₄ i s discussed from the photoluminescence properties and lower hydrogen content in that film.

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Synthesis of ammonia from H₂ and N₂ was examined at room temperature under the condition of glow discharge plasma in the presence of MgO. The rate of ammonia formation was significantly improved by MgO, although MgO was catalytically inactive in thermal ammonia synthesis. The amount of ammonia formed increased correspondingly with the increase of the surface area of MgO. The presence of considerable amount of ammonia on the MgO surface was observed by temperature programmed desorption. Trace of Mg₂N₃was detected on the MgO surface by ESCA. This was not an intermediate of the reaction, because ammonia formation was not observed by the reaction of Mg₂N₃ with hydrogen plasma.

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The surface fluorination of PET films under low pressure electric discharge was studied. The carbon tetrafluoride gas was used as fluorine source for fluorination in the discharge plasma. The contact angle of the water drop on the polymer surface was measured because it was related to the degree of surface fluorination. When the discharge began, the contact angles increase rapidly and reached 110° or more after a few minutes. The surface products were analysed by ESCA. We concluded that fluorine atoms were interpolated into the polymer molecules as -CF₂-.

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