Dynamics of the H+D/sub 2/. -->. HD+D reaction: Dependence of the product quantum state distributions on collision energy from 0. 98 to 1. 3 eV
Measurement of the nascent HD product rotational and vibrational state distributions for the H+D/sub 2/..-->..HD+D reaction is reported. Ultraviolet photolysis of HI using a pulsed laser at 291 or 280 nm is used to create H atoms in an HI/D/sub 2/ gas mixture, giving H+D/sub 2/ collisions with relative energies of 0.98 or 1.1 eV. Pulsed-laser coherent anti-Stokes Raman scattering (CARS) spectroscopy is used to record rotationally and vibrationally resolved Raman spectra of the HD product of the photolytically initiated H+D/sub 2/ reaction, under effectively single-collision conditions. The HD product quantum state distributions are extracted from these CARS spectra. The present data are combined with results we obtained previously at 1.3 eV collision energy to reveal the collision energy dependence of the product quantum state distributions. We find that at all three collision energies the product distributions can be quite accurately represented by a linear rotational and vibrational surprisal function. The rotational surprisal parameter is large, positive, and nearly constant (theta/sub R/ = 3.0--3.5) over this energy range, indicating a strong and consistent dynamical bias against product rotational excitation. The vibrational surprisal parameter, in contrast, varies much more, and is not even a monotonic function of collision energy (lambda/sub V/ = 2.2, 3.3, and 2.6 at 0.98, 1.1, and 1.3 eV, respectively). This behavior indicates enhancement of the cross section for the vibrationally nonadiabatic reaction channel at certain energies. At all collision energies 69%--73% of the available energy appears as translational energy of the products, with 22%--24% in rotation, and only 4%--7% in vibration.
- Research Organization:
- University of California, Los Alamos National Laboratory, Chemistry Division, Los Alamos, New Mexico 87545
- OSTI ID:
- 6174515
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 82:3; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
CHEMICAL REACTIONS
COLLISIONS
DEUTERIDES
DEUTERIUM
DEUTERIUM COMPOUNDS
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
EV RANGE
EV RANGE 01-10
EXCITED STATES
HYDROGEN
HYDROGEN COMPOUNDS
HYDROGEN DEUTERIDE
HYDROGEN ISOTOPES
ISOTOPES
LASER SPECTROSCOPY
LIGHT NUCLEI
MOLECULE COLLISIONS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
RAMAN SPECTROSCOPY
ROTATIONAL STATES
SPECTROSCOPY
STABLE ISOTOPES
VIBRATIONAL STATES