No abstract

Rate constants kQ for collisional quenching of A 2Σ+, v′=0, OH and OD have been measured for specific rotational levels N′ of the radical and a wide variety of collision partners. Through measurements of the time-dependent laser-induced fluorescence in a low pressure discharge flow at room temperature, we observe a decrease in kQ with increasing rotational quantum number for most quenchers. The internal levels of the collision pairs appear unimportant from experiments involving deuterium substitution. A comparison of rotationless rates for different colliders [kQ(N=0)] with calculations based on collision complex formation indicate that attractive forces play a role in the quenching process.

We report two complementary experimental investigations of the absorption spectrum of molecular oxygen between 243 and 258 nm. In the first experiment, excitation of O2 is inferred by detecting oxygen atoms resulting from chemical reaction. In the second experiment, absorption by O2 is observed directly by cavity ring-down spectroscopy. Absorption strengths for the Herzberg I [Formula: see text], Herzberg II [Formula: see text], and Herzberg III [Formula: see text] band systems are modeled with the DIATOM spectral simulation computer program using the best available branch intensity formulas. Absolute oscillator strengths are derived for all three systems and compared with values in the literature.