No fieldfree rotational transitions have been measured
for silylidyne. An extensive set of infrared transitions
has been published by
(1) M. Betrencourt, D. Boudjaadar, P. Chollet,
G. Guelachvili, and M. MorillonChapey,
1986, J. Phys. Chem. 84, 4121.
Electronic A ^{2}Δ – X ^{2}Π
transitions were reported by
(2) R. S. Ram, R. Engleman Jr., and P. F. Bernath,
1998, J. Mol. Spectrosc. 190, 341.
These data were subjected to a combined fit. A small
number of transitions with large residuals has been omitted
from the fit. Two of the four main hyperfine coupling
parameters were determined experimentally
in
(3) J. M. Brown, R. F. Curl, and K. M. Evenson,
1984, J. Phys. Chem. 81, 2884;
the remaining two were estimated based on ab initio
calculations. The resulting predictions are sufficiently
accurate, but should, nevertheless, be viewed with
some caution.
SiH is closer to Hund's case (a) at small quantum numbers.
The ground state spinflip transitions are weak
for SiH; they are predicted near 4540.6 and
4543.4 GHz.
These transitions are much stronger in CH, were they occur
near 532.8 and 536.8 GHz.
The ab initio ground state dipole moment
was taken from
(4) W. Meyer and P. Rosmus,
1975, J. Phys. Chem. 63, 2356.
These appear to represent the only highlevel calculations
involving vibrational corrections which are very
important because of the very small size of the dipole
moment.
