Theoretical and experimental investigation of pressure broadening and lineshift of carbon monoxide in collision with hydrogen between 8 and 600 K

We have measured pressure broadening and line shift parameters for the J=1 <-- 0 and J=2 <-- 1 transitions of carbon monoxide (CO) in collision with h ydrogen (H-2) at various temperatures between 8 and 600 K. Because of the a bundance of both species in the interstellar medium, the CO-H-2 collision s ystem is of astrophysical importance. Measurements below 35 K were made usi ng the collisional cooling technique, while measurements at higher temperat ures were made in a conventional equilibrium cell. These measurements were compared with theoretical results of quantum scattering calculations using the currently best available potential surface for the CO-H-2 collision sys tem. We find a good agreement between theory and experiment at higher tempe ratures (> 30 K) while for lower temperatures considerable deviations occur . (C) 2000 American Institute of Physics. [S0021-9606(00)01108-9].