Species tag 034501
Date of EntryMay 2013
ContributorH. S. P. Müller

Phophine is an oblate, near spherical rotor, similar to ammonia. The off-diagonal centrifugal distortion term ε causes a splitting between respective A1 and the A2 levels for K = 3n, with n > 0, which increases rapidly with increasing J and decreasing K. Tunneling is not important in phosphine. With respect the the first entry from Oct. 2008, the spectroscopic parameters have been reevaluated by
(1) H. S. P. Müller, 2013, J. Quant. Spectrosc. Radiat. Transfer 130, 335.

The main effect occurs for the intensities of ΔK = 3 transitions. In addition, some uncertainties have been reassigned. Pure rotational transition frequencies with ΔK = 0 were taken from
(2) G. Cazzoli and C. Puzzarini, 2006, J. Mol. Spectrosc. 239, 64

for J" ≤ 2; those with J" = 3 were taken from
(3) S. P. Belov, A. V. Burenin, L. I. Gershtein, A. F. Krupnov, V. N. Markov, A. V. Maslovsky, and S. M. Shapin, 1981, J. Mol. Spectrosc. 86, 184
In addition, higher-J transitions have been recorded by far-infrared spectroscopy by
(4) L. Fusina and M. Carlotti, 1988, J. Mol. Spectrosc. 130, 371
Furthermore, weak K = 3 splitting transitions and ΔK = 3 transitions have also been measured and used in the fit. These were reported by
(5) P. B. Davis, R. M. Neumann, S. C. Wofsy, and W. Klemperer, 1971, J. Chem. Phys. 55, 3564;
(6) F. Y. Chu and T. Oka, 1974, J. Chem. Phys. 60, 4612;
(7) D. A. Helms and W. Gordy, 1977, J. Mol. Spectrosc. 66, 206
and from
(8) S. P. Belov, A. V. Burenin, O. L. Polyanski, and S. M. Shapin, 1981, J. Mol. Spectrosc. 90, 579
C. Puzzarini is thanked for providing the data from (2).
Transition frequencies with uncertainties larger than 0.15 MHz were not merged.
Transitions with ΔK = 0 and with predicted uncertainties exceeding 5 MHz should be viewed with caution; the same applies to transitions with ΔK ≠ 0 and predicted uncertainties larger than 0.5 MHz. In the case of astronomical observations, the predictions should be reliable throughout.
Even though 31P and H hyperfine structure have been resolved in some of the laboratory experiments such splitting is negligible for astronomical observations.
At low temperatures, it may be necessary to discern between A-PH3 and E-PH3 The A state levels are described by K = 3n, those of E state by K = 3n ± 1. The nuclear spin-weight ratio is 2 : 1 for A-PH3 with K > 0 and all other states, respectively. Note: The A1/A2 splitting may be resolvable in astronomical observations. The JK = 11 level is the lowest E state level. It is 8.3711 cm–1 above ground.
Note also that the parity employed here differs from the A1/A2 parity as well as from the A+/A parity. A levels with + parity belong to A1 for even K and to A2 for odd K. A levels with + parity belong to A+ for J + K even and to A for J + K odd. Additional confusion may occur because the + sign has been omitted and transitions with rounded A1/A2 splitting of less than 0.1 kHz splitting have been merged. These transitions look like they were between two A1 levels. Lower case characters designate – parity states with K ≥ 10.
The dipole moment was determined in (5).

Lines Listed2095
Frequency / GHz< 8780
Max. J34
log STR0-18.0
log STR1-12.0
Isotope Corr.-0.0
Egy / cm–10.0
 µa / D 
 µb / D 
 µc / D0.57395
 A / MHzB
 B / MHz133480.128
 C / MHz117489.43
detected in ISM/CSMtentatively

Database maintained by Holger S. P. Müller and Sven Thorwirth, programming by D. Roth and F. Schloeder