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The conformer II of glycine is approximately
700 cm–1 or 1000 K higher in
energy than conformer I. Therefore, this conformer may be
observable only if it is not thermalized with
respect to conformer I.
This conformer has an intermolecular H bond between the H
atom of the carboxyl group and the N atom of the amino
group.
The microwave frequencies have been reported by
(1) F. J. Lovas, Y. Kawashima, J.-U. Grabow, R. D. Suenram,
G. T. Fraser, and E. Hirota,
1995, Astrophys. J. 455, L201.
The millimeter wave frequencies have been reported by
(2) V. V. Ilyushin, E. A. Alekseev, S. F. Dyubko,
R. A. Motiyenko, and F. J. Lovas,
2005, J. Mol. Spectrosc. 231, 15.
Predictions of transitions with ΔKa > 0
should be viewed with some caution because only a very small number of
b-type transitions have been observed. Extrapolations are assumed
to be reliable as long as the predicted uncertainties do not exceed
1 MHz.
The 14N hyperfine splitting was resolved in (1).
It may be resolved in cold sources or at lower frequencies.
Therefore, separate
predictions with hyperfine splitting are provided for J up to 10.
The partition function takes into account the spin multiplicity
gI = 3 of the 14N nucleus !
Glycine II has several low-lying vibrational modes; the lowest one is at
about 87 cm–1 or 104 K.
No vibrational state was considered in the calculation of
the partition function ! Moreover, the partition function
of conformer II does NOT take into account the energy
difference between conformer I and II !
The dipole moment was reported in (1).
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