The spectra of fluoroform (CF3H) in the solvents Ar, Nz, and Xe have been o
btained in the fundamental region (400-4000 cm(-1)) using a low temperature
cryostat and a Fourier transform infrared spectrophotometer. Ab initio cal
culations at the HF/6-31G* level have been performed to obtain the calculat
ed vibrational frequencies of the isolated CF3H molecule and CF3H in the pr
esence of the solvents (Ar, N-2, and Xe). Comparison of the frequency shift
s of CF2H in solution with respect to the gas phase frequencies is made for
the experimental and theoretical results. Lorentzian functions were used t
o fit the bands and obtain the wavenumber at the peak absorbance and the vi
brational band widths. An analysis of the dynamics of relaxation has been m
ade based on the infrared time correlation functions for three of the funda
mental modes (v(1), v(3), and v(4)). Bandwidths, band moments, and relaxati
on times were obtained by appropriate fitting of the experimental correlati
on functions to theoretical models. In liquid argon, the temperature depend
ence of the second moment (M-2) indicates that rotational relaxation explai
ns the bandwidth of the v(3) mode. For the v(4) mode, the temperature depen
dence of M-2 can be attributed to rotational relaxation if it is corrected
with a Coriolis coupling term. The bandwidths of the v(1) mode do not follo
w the rotational relaxation model, and probably vibrational relaxation is t
he dominant mechanism.