Pressure shifts and pressure broadening of the B and γ bands of oxygen

Measurements of pressure shift and pressure broadening in molecular oxygen have been made for rotational transitions in the B (1 <--0) and gamma (2 <--0) vibrational bands of the b(1) Sigma(g)(+) <-- X(3)Sigma(g)(-) visible electronic transition. The absorption features were. 9 9 measured simultaneously in two cells by photoacoustic spectroscopy using a scanning dye laser. The measurements were made with background gases of both pure oxygen and air at room temperature. The pressure shifts were all negative. The measurements show the magnitude of the pressure shift increasing with vibrational quantum number when compared with existing data for the A (0<--0) band. The shifts also increase with rotational number within each vibrational band. The shifts in air are larger than in oxygen although the difference gets smaller with vibrational number. The average shifts in air for the A, B, and gamma bands were 36, 11, and 0.2% higher, respectively, than in pure oxygen. The pressure broadening of the rotational lines does not change significantly with vibrational number and in general decreases with rotational number within a band. The pressure shift measurements were used by the high-resolution Doppler imager (on the Upper Atmospheric Research Satellite) to correct the Doppler wind measurements. (C) 2002 Elsevier Science (USA).