Evaluation of Molecular Quadrupole Moments from Broadening of Microwave Spectral Lines. I. Measurements

Abstract

The antimodulation method has been applied in a Stark cavity spectrometer to obtain pressure‐broadening constants of OCS, CHF3, and N2O both for self‐broadening (Λaa) and for foreign‐gas broadening (Λab) with H2 HD, D2 N2 NO, and CO2 as (nonabsorbing) broadeners. The results are (in megahertz torr−1) J = 1→2 transition of OCS:ΛOCS,OCS= 6.44, ΛOCS, H2 = 6.10, ΛOCS,HD= 6.10, ΛOCS,D2 = 5.57, ΛOCS,N2 = 4.41, ΛOCS,NO= 4.15, ΛOCS,CO2 = 5.13; J = 0→1 transition of CHF3: ΛCHF3 : ΛCHF3 ,CHF3 = 34.2, ΛCHF3,H2 = 4.9, ΛCHF 3,D2 = 4.3, ΛCHF3,N2 = 4.1, ΛCHF3 ,NO= 3.55, ΛCHF3 ,CO2= 6.65; J = 0→1 transition of N2O: ΛN2O: ΛN2O,N2O= 5.22, ΛN2O,H2 = 5.15, ΛN2O,D2 = 4.20, ΛN2O,N2 = 3.89, ΛN2O,NO= 3.65, ΛN2O,CO2 = 4.12. As a byproduct of these measurements, peak intensities (αmax) of the above transitions were obtained. In a subsequent paper, molecular quadrupole moments will be derived from the measured broadening constants.