Recent investigations of infrared laser induced chemical reactions are reviewed with parti-cular emphasis on the mechanism of collisionless multiphoton dissociation of molecules. The experimental results of isotope separation performed by TEA CO2 laser irradiation of SF6 reported in a number of papersand our research of the infrared photoreaction of C2F3Cl are described indetail. Theoretical analysis of the dissociation based on the RRKM model ofunimolecular reaction suggests that the exciation energy in SF6 is completely randomized in all its vibrational modes, while in C2F3Cl the absorbed energy is localized in a small number of vibrational modes. Furthermore, intensive and extensive studies of isotopeseparation, chemical reactions and isomerizations, carried out by using the infrared laser, are also reported. Itis briefly mentioned that CW infrared laser irradiation gives rise to collectiveexcitation of molecules, producing chemical reaction in liquid state.
A 50 meter modified Michelson interferometer has been installed in an underground tunnel in the Nagatsuta campus of Tokyo Institute of Technology. It is enclosed by vacuum pipes and illuminated by a frequency stabilized 633 nm He-Ne laser. The displacement of the interference fringes is converted to voltage with an accuracy of about 1×10-10. From the spectral analysis of the fluctuations of the interference fringes, it is found that the power spectral densityof the microtremor at the quiet time has peakes at 1 cycle/day and its har-monics, also at 0.3, 0.6, and 3 Hz, and that the values at around 10 Hzincrease when cars pass by on the road near the tunnel.
The optical properties of BBOT dye vapor excited by a N2 laser are measured in detail. The vapor phase spectra observed shift about 30nm to shorter wavelengths as compared with that in dioxane solvent. The vapor pressure is estimated to be 3_??_4 torr at about the temperature giving the maximum of fluorescenceintensity. The quantum efficiency decreases with temperatures and at 320°C is nearly equal to 0.4. The thermal dissociation of BBOT molecule is small below 320°C. The maximum gain of 0.2cm-1 (at 65kW pumping) occurs at 316°C and the peak wavelength of the gain curve is about 432nm. These results predict the possibility of laser emission in BBOT dye vapor by using the optical cavity of high Qvalue and higher pumping power.
Absorbers of cobalt stearate monomolecular layers were deposited on vacuum-evaporated-metal substrates by the Blodgett method. Relative intensity of monochromatic photoelectrons emitted from the substrates was measured for various absorber thickness and various electron emission angles. The absorbers were labeled with 14C. The uniformity of the deposited absorb-ers was confirmed by their autoradiography, and the decrease of absorber amount due to desorption was determined by the measurment of remaining radioactivity of the absorber. The anisotropical transmission due to the ordered structure of the absorber was not observed. At 0.5keV, the escape depth slightly increased with emission angle, but above 1 keV it did not depend on emission angle. The escape depth of 0. 5keV-electrons varied slightly from 25 Å at emission angle 10° to 30Å at 45°, while those of 1.4keV-electrons were 40 Å and 41 Å, respectively. The present values are about one third of those recently reported for organic matter appearing in other papers.
Method of producing high quality blazed ionetched holographic gratings was studied. The diffraction efficiency at 440 nm reached 73% for Littrow mount without degradation of the wavefront quality. The resolution and the stray light performances were controlled by selection of the sub-strate material and ion-etchingcondition, and were neary equal to those of conventional mechanically ruled gratings.
Simultaneous measurements of TSEE, TSL and TSC have been carried out on MgO single crystals excited by U. V.-rays, X-rays or γ-rays. It is suggested from the spectral distribution of OSEE and the effect of optical bleaching on the exoelectronemission that Vcenters produced by irradiation play a major role for the above phenomena. The holes released thermally or optically from the Vcenters to the valence band migrate to some electron traps (probably Cr2+ and Fe2+), where they recombine with trapped electrons with emission of TL light or exoelectrons. The exoelectron emission is discussed in terms of an Augerlike mechanism. It is found from the dependence of TSEE on the dose of U. V.-rays and X-rays that MgO can be used as a basic material of EE dosimeter.