Articles you may be interested inStatetostate cross sections for rotational excitation of OH by collisions with He and Ar J. Chem. Phys. 99, 8713 (1993); 10.1063/1.465595 Rotationalleveldependent quenching of A 2Σ+ OH and OD J. Chem. Phys. 82, 4022 (1985); 10.1063/1.448843High field level crossing measurements of the A 2Σ+ state of OD Radiative and predissociative lifetimes of the V′=0, 1, and 2 levels of the A 2Σ+ state of OH and OD A pulsed dye laser has been used to excite OH and OD radicals to the A 2~ + state and the quenching and vibrational relaxation cross sections have been measured for several different buffer gasses. It was found that the quenching cross sections were reasonably constant within a given vibrational level and tended to increase at higher vibrational levels. The vibrational relaxation cross sections decreased for higher rotational states and were generally smaller for collisions in which V changes by two than for collisions where it changes by only one. Finally, the implications of these measurements to the detection of OH in the atmosphere are discussed.
A direct measurement of the fluorescent decay rates of the V ′=0, 1, 2 vibrational levels of the A 2Σ+ state of OH and OD has been performed using pulsed laser excitation and at total gas pressures of less than 1 mTorr. The present experiment is the first in which lifetime measurements have been performed for individual rotational levels (N ′) of each of the three lowest vibrational states of both OH and OD and at pressures where both quenching and excitation transfer should be minimal. The radiative lifetime was found to increase slightly for the higher vibrational levels in agreement with a model of linear decrease of the transition moment with increasing internuclear separation. The measured radiative lifetimes, τV ′± (3σ), for OH were τ0=693±30 nsec, τ1=736±33 nsec and for OD were τ0 =691±27 nsec, τ1=712±30 nsec, τ2=736±39 nsec. The V ′=2 level of OH was found to be strongly predissociated with a predissociation lifetime of about 270±25 nsec at N ′=1. An analysis of the energies at which predissociation occurs leads to the conclusion that the repulsive 4Σ− state is responsible for all the observed predissociations for V ′?2 in both OH and OD.
The fluorescent decay of the A 2Σ+ (V′ = 0) state of OH and OD has been measured for N′ ? 8 for OH and N′ ? 9 for OD using pulsed dye laser excitation and at total gas pressures ? 1 mtorr. For the rotationless molecule, a radiative lifetime of 0.688 ± 0.021 μsec for OH and 0.692 ±0.021 μsec for OD was obtained, where the error bars are three standard deviations. In addition, OH exhibited a 8 ± 2% lengthening of the radiative lifetime between N′ = 1 and N′ = 8.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.