The low-frequency vibration rotation bands of the ammonia molecule

Tunable Spin-Flip Laser and Infrared Spectroscopy

“…The appearance of the low-energy bremsstrahlung structure in the region of alignment of the beam with the periodic structure of the crystal suggests the possibility of coherent bremsstrahlung effects. Such an enhancement of the lowenergy part of the photon spectrum was predicted by Dyson and Uberall, 6 and discussed in more detail by Uberall. 6 A relativistic electron (or positron) of energy E interacts coherently with a low-energy bremsstrahlung photon of wavelength A over a path length L &\(E/rn 0 c 2 ) 2 , and for an aligned particle the photon intensity is expected to be enhanced by a factor N, equal to the number of crystal atoms contained in the coherence length L. If d is the lattice spacing, then N=L/d.…”

“…The numbers on the peaks identify the transitions. The interesting point is that the sP(6,1) and sP (6,2) are resolved in our trace c The spacing is seen to be -0 C 05 cm"" 1 . This confirms our earlier estimate of a spin-flip Raman-laser linewidth of ^0.03 cm -1 .…”

Ammonia monitoring near 15 µm with diode-laser absorption sensors

“…Moreover, spectroscopic databases such as GEISA 9 and Hitran96 10 do not contain ammonia's near-IR spectra. Although there are many published papers that discuss NH 3 monitoring at 1.5 m, [11][12][13][14][15][16][17][18][19][20][21] and many papers that address fundamental NH 3 spectroscopy at other wavelengths, [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] few investigate the fundamental spectroscopic parameters at 1.5 m. However, two papers by Lundsberg-Nielsen et al are available that catalog extensively the lines, positions, and strengths of NH 3 absorption at 1.5 m. 38,39 Unfortunately, this research was performed in the optically thick regime, distorting the line-strength measurements for the strongest NH 3 lines and making the features difficult to resolve. Moreover, a recent paper by Modugno 3 38,39 and from Hitran96 for the 2.0-and 2.3-m bands of ammonia and all the H 2 O and CO 2 bands.…”

Thev2spectrum of NH3

“…The strongest line, sQ (3,3), has a strength of 13.3 cm -2 atm -1. The weakest line, aQ (17,1), has a strength of 1.2x 10-7cm-Zatm -1. Several dozen forbidden transitions are not included in this list.…”

“…The classic early work on the v 2 band of NH 3 was reported by Garing et al [1]. A higher resolution study was more recently published by Urban et al [2].…”