Nonresonant Microwave Absorption and Electric Dipole Moment of NO in the Gaseous State

Abstract

The microwave absorption in NO has been measured by a resonant cavity method at frequencies near 9 and 23 kMc/sec and at pressures in the range 3 to 27 atmos. The major part of the absorption is due to direct Λ-type doublet transitions, although at the higher pressures, a significant contribution also comes from the low frequency wings of the pure rotational spectrum. Since the Λ-doublet separation is much smaller than the applied frequency for all significant transitions, the resulting spectrum has the nonresonant or Debye shape. From the intensity of this spectrum, the electric dipole moment was found to be 0.148±0.002 debye. The effective collision cross section for random spacial reorientation of the molecules is approximately twice the kinetic collision cross section.