Collision Broadening of Rotational Absorption Lines. IV. Pressure Broadening of the Ammonia Inversion Spectrum

Abstract

The collision broadening of the NH₃ inversion spectrum was investigated within the framework of an earlier proposed theory of pressure broadening. The original treatment must be modified before application to NH₃ to allow for the fact that NH₃ has two closely spaced energy levels, the inversion doublet, with all other levels very widely spaced. This situation results in a “two‐level resonance” system which greatly affects the linewidth. In general, the agreement between the calculated and experimental values is very good although the calculated values tend to be slightly smaller. Molecular quadrupole moments for N₂ and H₂ are determined from linewidth data for broadening of NH₃ inversion lines and are in excellent agreement with values determined by other methods.