Influence of collisions on coherent IR multiphoton absorption in thiophosgene

Journal Article · Tue Sep 15 04:00:00 EDT 1981 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.442372· OSTI ID:6151414

Brenner, D M; Spencer, M; Steinfeld, J I

Absolute changes due to IR pumping in the intergrated rotational population of the vibrationless level (000000) of thiophosgene have been measured under beam conditions and bulb conditions (1--1000 mTorr). Under collisionless conditions, large decreases are observed which reflect depopulation of all rotational states at a single CO/sub 2/ laser frequency. At higher thiophosgene pressure, less depopulation occurs; zero depopulation of the vibrationless level is observed at pressure > or = 300 mTorr within experimental uncertainty (< or = 3%). The latter agrees with measurements of the average number of photons absorbed from photoacoustic data (0.013 +- 0.001) obtained at a pressure of 500 mTorr. The results support a mechanism of coherent pumping in the low density of states regime and the existence of a long range, collision-induced dephasing interaction which has a cross section >> gas kinetic.

• Research Organization: Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973
• OSTI ID: 6151414
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 75:6; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular &amp; Chemical Physics-- Atomic &amp; Molecular Properties &amp; Theory
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTRA
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
EXCITED STATES
INFRARED RADIATION
MEDIUM VACUUM
OPTICAL PUMPING
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PRESSURE DEPENDENCE
PUMPING
RADIATIONS
ROTATIONAL STATES
SPECTRA
THIOPHOSGENE