F. Di Teodoro et al., Collisional quenching of CO B (1)Sigma(+)(v(')=0) probed by two-photon laser-induced fluorescence using a picosecond laser, J CHEM PHYS, 113(8), 2000, pp. 3046-3054
We report measurements of room-temperature, species-specific quenching cros
s sections of CO B (1)Sigma(+) (v' = 0) in collisions with He, Ne, H-2, N-2
, Ar, CO, Kr, CH4, O-2, Xe, CO2, C3H8, and H2O. The measured quenching cros
s sections (in Angstrom(2)) were 0.25 +/- 0.02, 0.54 +/- 0.04, 11.0 +/- 0.4
, 24.6 +/- 0.5, 27.7 +/- 0.5, 37 +/- 2, 42 +/- 2, 81 +/- 4, 85 +/- 5, 99 +/
- 6, 133 +/- 5, 144 +/- 7, and 170 +/- 8, respectively. Two-photon excitati
on of the CO molecules via the Hopfield-Birge system (X (1)Sigma(+)-->--> B
(1)Sigma(+)) was performed using the frequency-tripled 690 nm emission of
a custom-built picosecond dye laser. Blue-to-green fluorescence in the Angs
trom bands (B (1)Sigma(+)--> A (1)Pi) was detected using a microchannel-pla
te photomultiplier tube and recorded with a digital storage oscilloscope. T
he quenching cross sections were directly obtained by time resolving the te
mporal decay of the fluorescence signal and observing its variation as a fu
nction of the quencher pressure. The effect of radiative trapping on the ob
served fluorescence was also quantitatively modeled. (C) 2000 American Inst
itute of Physics. [S0021-9606(00)02332-1].