COLLISION-BROADENING AND COLLISION-SHIFT OF NO GAMMA(0,0) ABSORPTION-LINES BY H2O, O-2, AND NO AT 295-K

Isolated features within NO A <-- X (0,0) near 225 nm were fully resolved in absorption across a static cell at room temperature (295 K) using the frequency-doubled output of a cw, rapid-tuning ring dye laser. These lines were perturbed by a single bath species, either O2, NO, or H2O, and were fit to Voigt profiles to extract values for the collision-width (2gamma) and -shift (delta) coefficients. Both coefficients were essentially constants, independent of the ground state rotational energy, for any one perturber. For O2, NO, and H2O perturbers, 2gamma was measured to be 0.53, 0.55, and 0.79 cm-1 atm-1, respectively. The companion measurements of delta were -0. 16, -0.17, and -0.21 cm-1 atm-1. Inferred from the measurements of delta were upper bounds on the van der Waals energy constants for the NO A state. All perturbers induced slight asymmetries and narrowing of the lineshape. (C) 1994 Academic Press. Inc.