Dissociative excitation of water by metastable rare gas atoms: Rg(/sup 3/P/sub 0,2/)+H/sub 2/O. -->. Rg+OH(A /sup 2/. sigma. /sup +/)+H (Rg = Ar,Kr)

Journal Article · Fri Jan 15 04:00:00 EST 1988 · J. Chem. Phys.; (United States)

OSTI ID:5646467

Tabayashi, K; Shobatake, K

The title reactions were studied over the relative collision energy range 0.3--1.8 eV in crossed molecular beams. Vibrational and rotational state distributions of the nascent OH(A /sup 2/..sigma../sup +/) product were determined by analysis of fluorescence from the OH(A /sup 2/..sigma../sup +/--X /sup 2/Pi) bands. The rotational distributions could be represented by simple Boltzmann distributions. With Ar*(/sup 3/P/sub 0,2/) excitation, both vibrational and rotational distributions were found to have no significant dependence on the collision energy and compare well with results previously obtained at near-thermal energies. With Kr(/sup 3/P/sub 0,2/) excitation, however, the state distributions were found to be strongly collision-energy dependent, the rotational temperature T/sub r/ (v = 0) increasing from 850 to 1750 K and the vibrational population ratio N/sub v//sub //sub = //sub 1//N/sub v//sub //sub = //sub 0/ from less than or equal to0.09 to 0.14 as the collision energy was increased from 0.35 to 0.65 eV. Time-of-flight (TOF) energy selection was used to measure the integral cross sections for the formation of the OH(A). The collision energy dependence of the cross section for the reaction Ar(/sup 3/P/sub 0,2/) +H/sub 2/O..-->..Ar+OH(A /sup 2/..sigma../sup +/)+H was found to be negative, whereas that for the reaction Kr(/sup 3/P/sub 0,2/)+H/sub 2/O..-->..Kr +OH(A /sup 2/..sigma../sup +/)+H exhibited a positive dependence. To understand the above experimental findings, possible mechanisms for the formation of OH(A /sup 2/..sigma../sup +/) from Rg(/sup 3/P/sub 0,2/)+H/sub 2/O are considered that are consistent with the hypothesis that the reaction is governed by spin conservation.

• Research Organization: Institute for Molecular Science, Okazaki 444, Japan
• OSTI ID: 5646467
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 88:2; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
BEAMS
COLLISIONS
DISSOCIATION
DISTRIBUTION
ELEMENTS
ENERGY LEVELS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EV RANGE
EXCITATION
EXCITED STATES
FLUIDS
FLUORESCENCE
GASES
HYDROGEN COMPOUNDS
LUMINESCENCE
MOLECULAR BEAMS
MOLECULE COLLISIONS
NONMETALS
OXYGEN COMPOUNDS
RARE GASES
ROTATIONAL STATES
WATER