Showing papers by "Yutaka Matsumi published in 1993"

Isotopic branching ratios and translational energy release of H and D atoms in reaction of O(1D) atoms with alkanes and alkyl chlorides

Abstract: H and D product atoms from the reaction of O( 1 D) with alkanes and alkyl chlorides have been measured by multiphoton ionization as well as by laser-induced fluorescence. Measured isotopic branching ratios [H]/[D] in the reaction of O( 1 D) with CH 3 CD 2 CH 3 , CD 3 CH 2 CD 3 , CD 3 CHClCD 3 , and CH 3 CDClCH 3 are almost statistical at collision energies, 8.1-9.1 kcal/mol. The Doppler profiles of the H atoms from the reactions of O( 1 D)+hydrocarbons (CH 4 , C 2 H 6 , and C 3 H 8 ) suggest that the translational energy released to the RO+H products is 8±1 kcal/mol and almost independent of the size of the alkyl groups

Dynamics of the reactions of O(1D) with HCl, DCl, and Cl2

Abstract: The reactions O(1D)+HCl→OH+Cl (1a) and OCl+H (1b), O(1D)+DCl→OD+Cl (2a) and OCl+D (2b), and O(1D)+Cl2→OCl+Cl (3) are studied at an average collision energy of 7.6, 7.7, and 8.8 kcal/mol for (1), (2), and (3), respectively. H, D, and Cl atoms are detected by the resonance‐enhanced multiphoton ionization technique. The average kinetic energies released to the products are estimated from Doppler profile measurements of the product atoms. The relative yields [OCl+H]/[OH+Cl] and [OCl+D]/[OD+Cl] are directly measured, and a strong isotope effect (H/D) on the relative yields is found. The fine‐structure branding ratios [Cl(2P1/2]/[Cl(2P3/2)] of the reaction products are also measured. The results suggest that nonadiabatic couplings take place at the exit channels of the reactions (1a) and (2a), while the reaction (3) is totally adiabatic.

Anisotropy and energy disposal in the 193-nm N2O photodissociation measured by VUV laser-induced fluorescence of O(1D)

Abstract: Laser-induced fluorescence near 115 nm has been used to measure the Doppler profile of the O( 1 D) product of 193-nm N 2 O photolysis. The anisotropy of product recoil vectors is characterized by the parameter β=0.50±0.05. The measured velocity distribution can be used to calculate a distribution of recoil energies that is in reasonable agreement with that reported recently by Felder, Haas, and Huber, an average of 27.3 kcal/mol is deposited into translation, leaving ≃37 kcal/mol for the internal excitation of the N 2 fragment

Photodissociation of ICI at 235-248 nm

Abstract: Photodissociation of iodine monochloride has been investigated at 235–248 nm by studying Doppler profiles of (2+1) resonance enhanced multiphoton ionization spectra of fragment chlorine atoms and two‐photon laser induced fluorescence spectra of iodine atoms. At 235.3–237.8 nm, a measured branching ratio of [Cl*(2P1/2)]/[Cl(2P3/2)] is 0.68±0.10. At 248 nm, the [I*(2P1/2)]/[I(2P3/2)] ratio is 0.71±0.27. From the measured Doppler profiles and the ab initio calculation, the photoprepared states leading to Cl and Cl* production are assigned to the 3Π0+ (and possibly 3∑−0+) and the 1Π1 states, respectively. Nonadiabatic couplings between the potential curves have been discussed.

Formation of a Hydrogen Atom from the Photodissociation of Hydrogen Peroxide at 193 nm

Abstract: Doppler profiles of H atoms from the photodissociation of H2O2 at 193 nm were measured by a laser-induced fluorescence method at 121.6 nm. On the average, 149 kJ mol−1 of energy is released as translational energy, which corresponds to about to 60% of the available energy. Doppler width anisotropy data show that the anisotropy parameter, β, for the photofragment angular distribution is −0.26 ± 0.11. This result implies that the H2O2 A1A state is responsible for H atom formation.

Photodissociation of Trimethylindium and Trimethylgallium on GaAs at 193 nm Studied by Angle-Resolved Photoelectron Spectroscopy

Abstract: The chemisorption and photodecomposition of trimethylindium (TMIn) and trimethylgallium (TMGa) on a GaAs(100) surface have been studied by means of angle-resolved X-ray and ultraviolet photoelectron spectroscopy. Increase in the substrate temperature from 150 to 300 K causes the In-C bond cleavage of the adsorbed TMIn to generate methyl radicals that react with Ga species in the substrate to form Ga-C bonds. The 193 nm irradiation of TMIn adsorbed on GaAs at 150 K induces the In-C bond cleavage. The carbon species desorb from the substrate. Irradiation at 351 nm causes no change in the X-ray photoelectron spectra of the adsorbed species. These results imply that photodissociation is not due to photoabsorption of the GaAs substrate but that of the adsorbed species on the substrate. Photoirradiation of 488 nm on TMIn adsorbed on GaAs at 150 K induces pyrolytic cleavage of the In-C bond.