Longpath Fourier Transform Spectra of Ammonia

Abstract

The ammonia molecule is known to be useful as a probe for studying conditions inside interstellar clouds and planetary atmospheres. Correct interpretation of interstellar and planetary spectra need to be supported by adequate laboratory measurements. in the present studies we report the high resolution Fourier transform spectra of ammonia recorded with a pathlength of 192m at the Kitt Peak National Observatory. Transitions with intensities that are two orders of magnitude weaker than those that have been reported earlier, have been observed and assigned. These include high J transitions, hot bands and forbidden transitions. These transitions are not saturated under long paths such as those available in planetary atmospheres and are therefore useful in the estimation of temperatures. The forbidden transitions have been processed with other relevant data to provide complete information on the energy levels. Such information is required for the calculation of equilibrium population of energy levels and partition functions, which go into the estimation of spectral intensities and abundances in terrestrial, interstellar and planetary atmospheres.