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 resol ved in absorption across a static cell at room temperature (295 K) usi ng 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 collisi on-width (2gamma) and -shift (delta) coefficients. Both coefficients w ere 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 v an der Waals energy constants for the NO A state. All perturbers induc ed slight asymmetries and narrowing of the lineshape. (C) 1994 Academi c Press. Inc.