Atmospheric chemistry deals with chemical compounds, especially trace gases, in the atmosphere and their origin, chemical reactions, accumulation and distribution.
The photochemistry and kinetics of free radical r eactions among trace substances are important for understanding chemical transformation of trace substances into other compounds, and finally, the ir removal from the atmospheric domain.
In this paper, rate constants a nd mechanisms for reactions of free radicals with other gases related to atmospheric chemistry will be reported. Studies are carried out using a photoionization mass spectrometer coupled with a discharge-flow or pulsed laser photolysis system. The photoionization mass spectrometer can be a very selective and sensitive detector of many free radicals in the gas phase. Vacuum ultraviolet light from rare gas resonance lines is used to ionize the radicals, rather than an electron beam, in order to avoid the interference from fragments heavier stable molecules. Rate constants for reactions o f alkyl, hydroxyalkyl, substituted methyl, formyl, and acetyl radicals with atomic and molecular oxygen have been measured and the reactivity of those reactions will be discussed by the correlation with ionization potential and electronegativities of radicals. In addition, rate constants for reactions of peroxy radicals such as HO₂ and CH₃O₂ with NO have been determined. Contribution of each reaction to atmospheric chemistry will be discussed.
Finally, an experime ntal study of ozone depletion by CFCl₃ using a 6m^-3 photochemical chamber is reported in order to show the decay of ozone by a catalytic cycle involving Cl and ClO radicals.

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Extrinsic photocarrier generation in a layered organic photoreceptor consisting of triphenylamine trisazo pigment-based carrier generation layer (CGL) in combination with N, N-dipheny-4-biphenylylamine derivative-based carrier transport layer (CTL) was investigated in order to clarify the carrier generation pathways and to improve the carrier generation efficiency. As a result, extrinsic photocarrier generation was proven to occur via following reaction pathways; ( i ) exciton produced by photon absorption in the bulk of the CGL diffuses to the CGL/CTL interface, ( ii ) the exciton makes photoinduced electron transfer to generate geminate pair at the interface which competes with the deactivation of the exciton, and ( iii ) the geminate pair dissociates into free carriers which competes with the geminate recombination. The overall photocarrier generation efficiency was expressed by using these reaction rates; and the way to develop the efficiency was discussed based on four elementary processes involved. A small frequency factor of the electron transfer at the CGL/CTL interface suggests that a little number of N, N-dipheny-4-biphenylylamine derivatives make contact with the azo pigment.

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Electrochemical formation of dye films based on chromogenic development of photography was studied. Colored dye films were prepared on an indium tin oxide (ITO) electrode by controlled potential electrolysis (oxidation) of 1, 4-benzenediamine derivative (PPD) followed by a reaction with a coupler. Growth of the film stopped within a few minutes. The cessation of the growth was ascribed to coverage of the electrode with the film of electric insulation. Scanning electron micrographs of these films indicate that these films are uniform with thickness of 0.4∼0.5 μm. Appropriate combinations of PPD and coupler to give stable film were obtained by measuring the change of absorption spectra of the films after one month. The rate constants of deamination and dye formation of quinone diimine (QDI) were measured by cyclic voltammetry. Appropriate pH and concentrations of PPD and coupler for the film formation were discussesd by comparison of rate of the dye formation with that of the deamination. It was found that suitable pH of the film formation is 9 to 11 region. Failure of film formation in the lower concentrations of PPD and coupler was ascribed to the deamination of QDI.

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The synthetic reaction of 1, 3-cyclohexadiene by liquid phase dehydration of 2-cyclohexen-1-ol on the solid catalysts as zeolites and ion-exchange resins was studied.
More than 40% yield of 1, 3-cyclohexadiene was produced in the presence of H-ZSM-5 and ion-exchange resin; Amberlist-15, but low yield of that and dicyclohexenyl ether, main product, were formed on other zeolites.
The rea ction mechanism on H-ZSM-5 and ion-exchange resin was investigated. In the presence of ion-exchange resin, the reaction proceeds by the mechanism of the consecutive reaction forming inter mediate dicyclohexenyl ether by dehydration of two 2-cyclohexen-1-ol and formed 1, 3-cyclohexadiene is easily polymerized by the consecutive reaction. However, in the presence of H-ZS M-5, dicyclohexenyl ether was formed mainly on the acid site in the outer surface of H-ZSM-5 zeolite crystalline to be determined by the poison experiment of 4-methylquinoline. Within the pore of it, 1, 3-cyclohexadiene was obtained as main product by direct dehydration of 2-cyclohexen-1-ol and it did not polymerize depend on the shape selectivity of H-ZSM-5 to control the formation of dicyclohexenyl ether and polymer.
To study the reason why dicyclohexenyl ether was main product on other zeolites, the acid strength, pore size and the deactivation rate were determined. These results showed that the reaction st opped at the formation of intermediate dicyclohexenyl ether with large molecular diameter depend on the lo w acid strength and large pore size of H-Y. The otherhand, in the presence of H-fl and H-mordenite, 1, 3cyclohexadiene was able to be formed by their acid strength, but it was so easily transformed into polymer and the catalysts were so rapidly destroyed that the reaction stopped at the intermediate dicyclohexenyl ether.
Thus it is concluded that H-ZSM-5 is the best catalyst for synthesis of 1, 3-cyclohexadiene because the acid strength, deactivation and the shape selectivity not producing polymer.

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Analytical conditions for synchronous fluorescence spectrometry were optimized for the simultaneous determination of fluorene, carbazole and anthracene in polycyclic aromatic matrices. The precision of t he determination is improved by setting the wavelength interval (Δλ) accurately and by mi nimizing the ratio of a variation of the intensity to the deviation of Δλ. In the simultaneous determinati on by synchronous fluorescence spectrometry, the most suitable Δλ for one compound is not always applicable to other compounds. The determination, therefore, was carried out by using the most suitable Δλ for eac h compound. Fluorene, carbazole and anthracene were determined within 1.0% of RSD by measuring the synchronous fluorescence intensities at 301 nm (Δλ=13 nm), 318 or 331 nm (Δλ= 17 or 19 nm), and 357 or 376 nm (Δλ= 21 or 24 nm), respectively. The sensitivity of this method is comparable to tha t of the conventional fluorescence spectrometry, because Δλ can be adjusted to 13-24 nm. This method has been successfully applied to the determination of these compounds in anthracene cake.

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Adsorption-desorption phenomena of nitriles at a hanging mercury drop electrode were studied by a flow injection method with measuring differential capacity-time curves. The compounds investigated were acetonitrile, butyronitrile and valeronitrile. The adsorption of acetonitrile at 0.6 V is irreversible, that of valeronitrile at 0.6 V is reversible. A part of the adsorbed butyronitrile at 0.6 V is desorbed. When the adsorbed potential is changed, acetonitrile is adsorbed irreversibly between 0.4V and 0.6 V. At 0.7 V half of the adsorbed acetonitrile is desorbed. At 1.2 V acetonitrile is adsorbed reversibly. The adsorption of butyronitrile is irreversible between -- 0.45 V and 0.55 V. Half of the adsorbed butyronitorile is desorbed at 0.6 V. At the potential more negative than 0.7 V the adsorption of butyronitrile is almost reversible. The adsorption of valeronitrile is irreversible and it is reversible at the more negative potential than 0.5 V. The irreversibly adsorbed molecules of nitriles turn their cyano groups to the electrode and the reversibly adsorbed molecules of niriles turn their alkyl groups to the electrode. Water molecules at the primary water layer are replaced with the irreversibly adsorbed molecules. Water molecules not adjacent to the electrode or hydrated cations are replaced with the reversibly adsorbed molecules.

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Tetrahydrothiophene (THT) is one of the most commonly used gas odorant in Japan. To control quality of distribution gas, a simple method is required for determination of THT. In this study, gas detector tube which is able to determine THT in natural gas has been developed. This gas detector tube is composed of indicating layer tube and prelayer tube. The principle of coloration is oxidation of THT by KMnO₄. The authors investigated the effect of temperature, humidity and interfering substances (C₂H₄, C₃H₆, H₂S, C₂H₅SH) in test gas on length of coloration. The determination range of THT was also investigated. The results were as follows: (1) Determination range at 293 K was 10∼200 ppm (vol) when test gas volume was 100 mL. (2) C₂H₄, C₃H₆, H₂S and C₂H₅SH were no effect on length of coloration in concentration below 5000, 2000, 300 and 3.0 ppm (vol), respectively.

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Alkoxy (isocyanato) silanes were synthesized by the reaction of tri- or tetraisocyanatosilane with ethanol, isopropyl alcohol, or t-butyl alcohol. Due to the milder reactivity of the isocyanatosilanes compared with that of the corresponding chlorosilanes, the substitution reaction was easily controlled by proper molar ratio and use of bulky alcohol with an appropriate catalyst. As a result, alkoxy (isocyanato)silanes were prepared and isolated by distillation in high yields.

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In reductive methylation reaction of coals using molten potassium under ultrasonic irradiation, the relation between irradiation time in anionization and solubilization has been studied. Two kinds of coals of the different rank were allowed to react in various irradiation times (15∼180 min). In ultrasonic irradiation method in comparison with conventional method, it was observed that the number of introduced methyl groups and the total yield of soluble products increased remarkably at shorter reaction time. These results are due to thatthe scission of C-O-C bonds in coals, reductive methylation, and methylalion of aromatic compounds or OH groups were accelerated at the initial stage of the reaction, and also that lamination layer by aromatic stacking and entangled structure by long chain alkyl groups in higher rank coal (Kairan), entangled structure by long chain alkyl groups and bridged structure by OH groups in low rank coal (Kitadein) were relaxed, respectively, by ultrasonic irradiation.
Accordingly, the effect of ultrasonic irradiation on reductive methylation reacti on was influenced by the structure of original coals.

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Structural characteristics of the adducts of antitumor platinum complex with nucleotide (adjacent guanines (GpG)) have been investigated using ¹H-NMR spectroscopy. The reaction of dichloro (1R, 2S, 3R) -3-methylcyclohexane diamineplatinum ( I1) (abbreviated as Pt (RSR-dach) Cl₂) with GpG resulted in two geometrical isomers in which the Pt (RSR-dach) moiety crosslinked at the N7 positions of adjacent guanines. Structure of the two isomers, they differ from one another in relative orientation of the cyclohexane ring toward the GpG moiety, was assigned on the basis of ¹H-NMR data. Moreover, the influence of the GpG moiety on conformation of the Pt (RSR-dach), or vice versa, will be discussed between the both isomers. No differences in the conformation of the Pt (RSR-dach) moiety between the two isomers were observed, and it is likely that conformation about the phosphodiester bond of the GpG moiety is influenced by the orientation of the cyclohexane ring (Pt (RSR-dach) moiety).

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The aromatic nitro compounds are known to be highly toxic to metabolism of human, animals and plants primarily due to their potent interfering action. The solubilities of nitro compounds of aniline, phenol, anisole, toluene, benzoic acid, and benzene were measured at 20 °C by means of TOC (Total Organic Carbon) method (Table 1). The results of measurements suggest a correlation between the solubility (S) and the melting point (θ) of these aromatic nitro compounds (Figs.1, 2).
The relationship between logarithm of solubility and melting point is expressed a si mple equation as log S/μg mL^-1=aθ/°C+ b (1) in aromatic nitro compounds of aniline, phenol, anisole, toluene, benzoic acid and benzene (Table 2). It is concluded that the solubilities of aromatic nitro compounds can be presumed by measuring melting point.

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Crystalline phase of CeGaO₃ has been successfully synthesized by two kinds of methods; arc- and skull- melting methods. In the case of arc -melting method, CeGaO₃ is finally obtained by a reaction of Ce2O₃ and Ga₂O₃, where, Ce₂O₃ is produced by a “thermal effect on the reduction” from the source CeO₂ in the first reaction stage. On the other hand, in the case of skull-melting method, . CeGaO₃ is obtained by a “direct reduction” of Ga₂O₃ by Ce. Both crystallographic data on CeGaO₃ obtained by two methods are consistent. The structure belongs to tetragonal system with space group, P4/mmm, which is different from cubic system as reported in literatures. Lattice constants are a= 0.3873 (1) nm, c= 0.3880 (1)nm, V= 0.5819 (3) x 10^-28 m³, Z=1. This compound is unstable at high temperature in air and decomposes to CeO₂ and Ga₂O₃ by heating up to 1250°C.

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