Vibrational relaxation of acetylene and acetylene--rare-gas mixtures

Journal Article · Mon Apr 14 23:00:00 EST 1980 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.439721· OSTI ID:5411862

Haeger, J; Krieger, W; Rueegg, T; Walther, H

Vibrational relaxation of acetylene (C/sub 2/H/sub 2/) and acetylene--rare-gas mixtures has been investigated using laser-induced fluorescence. Time-dependent fluorescence signals from the vibrational modes ..nu../sub 2/ and ..nu../sub 5/ have been recorded, following excitation of ..nu../sub 3/ and (..nu../sub 2/+..nu../sub 4/+..nu../sub 5/) at 3300 cm/sup -1/ with pulses of a tunable optical parametric oscillator. The activation rate of ..nu../sub 2/ and ..nu../sub 5/ were estimated to be >880 ms/sup -1/ Torr/sup -1/ and >330 ms/sup -1/ Torr/sup -1/, respectively. The following V-T/R relaxation rates have been obtained from the decay of the ..nu../sub 5/ fluorescence signal: (12.7 +- 1.1) ms/sup -1/ Torr/sup -1/ for C/sub 2/H/sub 2/ as collision partner, (0.46 +- 0.05) ms/sup -1/ Torr/sup -1/ for Ne, (0.66 +- 0.06) ms/sup -1/ Torr/sup -1/ for Ar, (0.67 +- 0.04) ms/sup -1/ Torr/sup -1/ for Kr, and (0.57 +- 0.04) ms/sup -1/ Torr/sup -1/ for Xe. Surprisingly small V--V deactivation rates of the CC stretching vibration ..nu../sub 2/ have been measured. These are (21.3 +- 1.0) ms/sup -1/ Torr/sup -1/ for C/sub 2/H/sub 2/ collisions, (0.63 +- 0.06) ms/sup -1/ Torr/sup -1/ for Ne, (0.78 +- 0.08) ms/sup -1/ Torr/sup -1/ for Ar, (0.93 +- 0.09) ms/sup -1/ Torr/sup -1/ for Kr, and (0.77 +- 0.09) ms/sup -1/ Torr/sup -1/ for Xe. Acetylene relaxation mechanisms compatible with these rates are considered.

• Research Organization: Projektgruppe fuer Laserforschung der Max-Planck-Gesellschaft zur Foerderung der Wissenschaften e.V., D-8046 Garching, Federal Republic of Germany
• OSTI ID: 5411862
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 72:8; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ACETYLENE
ALKYNES
ARGON
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
COLLISIONS
DISPERSIONS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUORESCENCE
HYDROCARBONS
KRYPTON
LUMINESCENCE
MIXTURES
MOLECULE COLLISIONS
NEON
NONMETALS
ORGANIC COMPOUNDS
RARE GASES
RELAXATION
TIME DEPENDENCE
VIBRATIONAL STATES
XENON