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Molecular beam scattering studies of the reaction D + H 2 (v = 0) and D + H 2 (v = 1) → HD + H
Author(s) -
Goetting R.,
Toennies J. P.,
Vodegel M.
Publication year - 1986
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550180906
Subject(s) - chemistry , crossed molecular beam , atomic physics , excited state , excitation , ground state , adiabatic process , scattering , molecular beam , recoil , beam (structure) , cross section (physics) , hypersurface , molecule , physics , optics , organic chemistry , quantum mechanics , thermodynamics , mathematical analysis , mathematics
The reaction D + H 2 → HD + H has been investigated in two molecular beam scattering experiments. Angular and time‐of‐flight distributions have been measured for the initial vibrational ground state ( v = 0) at a most probable collision energy of E cm = 1.5 eV and for the first vibrational excited state ( v = 1) at E cm = 0.28 eV with the same apparatus. Results for the ground‐state experiment are compared with quasiclassical trajectory calculations(QCT) on the LSTH‐hypersurface transformed into the laboratory system and averaged over the apparatus distributions. The agreement isquite satisfactory. At this high collision energy the HD products are no longer scattered in a backward direction but in a wide angular region concentrated about θ = 90° in the center‐of‐mass system. The absolute reactive cross section has been determined and the agreement with the theoretical value from QCT calculations is within the experimental error. The high sensitivity of the experiment to different properties of the doubly differential cross section has also been demonstrated. A preliminary evaluation of the experiment with initial vibrational excitation ( v = 1) shows that the HD‐product molecules are preferably backward scattered and the change of internal energy is small supporting the concept of a reaction which is adiabatic with respect to the internal degrees of freedom.