Thev2spectrum of NH3

Abstract

The v ₂ spectrum of NH₃ has been obtained with a resolution of 0·0050 cm^-1 on the Kitt Peak McMath Fourier Transform spectrometer in the wavenumber range between 720 and 1300 cm^-1. 489 lines have been assigned up to J = 11 in the P branches, J = 17 in the Q branches and J = 16 in the R branches. A least squares analysis of this spectrum yields considerably improved term values and effective molecular constants for the v ₂ state. The root mean square deviation of the least squares fit is 0·00019 cm^-1. Our observed lines are in excellent agreement (root mean square deviation = 0·000050 cm^-1) with the limited number of laser heterodyne measurements that have been reported recently by Sattler and coworkers and by Hillman. The ground state energies have been revised to include our new determination of the C, D_K, H_K and L_K constants and have been extended to a higher J = 17 than given in our earlier report.