Infrared multiphoton excitation and inverse electronic relaxation in SO/sub 2/

Journal Article · Fri Aug 15 04:00:00 EDT 1980 · J. Chem. Phys.; (United States)

OSTI ID:5160395

Wolk, G L; Weston, Jr, R E; Flynn, G W

Visible luminescence (lambda=270--470 nm) has been observed from S/sup 16/O/sub 2/ and S/sup 18/O/sub 2/ at pressures of 0.2 to 20 Torr following irradiation by an intense infrared laser (lambda=9.3 ..mu..m). Our experiments show that the luminescence is not due to dielectric breakdown or recombination of dissociation fragments, but rather is fluorescence from the first excited singlet states of SO/sub 2/ following inverse electronic relaxation from highly excited vibrational levels of the ground electronic state. Crossover from the ground to excited electronic states may also be collisionally assisted. Spectroscopic and kinetic measurements are consistent with previous studies on /sup 1/B/sub 1/ emission from SO/sub 2/. The pressure dependence of the fluorescence yield exhibits two distinct pressure regimes, while the dependence of visible emission on laser pump wavelength follows the small signal infrared absorption spectrum. The threshold for detection of fluorescence is 17--20 J/cm/sup 2/ with 9.3 ..mu..m radiation as the excitation source. These observations are discussed in terms of recently proposed theories which describe the photophysics of vibrationally excited states coupled to a radiative continuum through higher electronic states.

• Research Organization: Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973
• OSTI ID: 5160395
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 73:4; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
CHALCOGENIDES
COUPLING
ELECTRONIC STRUCTURE
EMISSION SPECTRA
ENERGY LEVELS
EXCITED STATES
FLUORESCENCE
LUMINESCENCE
OXIDES
OXYGEN COMPOUNDS
PRESSURE DEPENDENCE
SPECTRA
SULFUR COMPOUNDS
SULFUR OXIDES
VIBRATIONAL STATES
VISIBLE SPECTRA