High resolution infrared spectra of the first and second stretching overtone band systems of 123SbD3

The high resolution infrared spectrum of the mono-isotopic species 123SbD3 has been studied in the regions of the first and second Sb-D stretching overtones, from 2600 to 2800 cm−1 and from 3900 to 4100 cm−1, respectively. In both regions only two almost degenerate bands of similar intensity have been observed, one parallel and the other perpendicular, corresponding to the low-lying states in the manifolds of the vstretching=2and3 excited vibrational states. These bands have been identified as 2ν1(A1)/ν1 + ν3(E) in the first overtone and 3ν1(A1)/2ν1 + ν3(E) in the second overtone band system. About 1700 transitions with Jmax′=Kmax′=20 have been assigned to the 2ν1(A1)/ν1 + ν3(E) and about 700 with Jmax′=Kmax′=21 to the 3ν1(A1)/2ν1 + ν3(E) dyad. The transitions assigned to each dyad have been fitted simultaneously since the A1/E excited states are affected by strong Coriolis and k-type perturbations treated explicitly in the model. Eventually, the extent to which the parameters resulting from the analyses fulfill the local mode theory requirements has been evaluated. Differently from SbH3, the deuterated species does not reach true local mode behavior, even in the second overtone.