High‐resolution stimulated Raman spectroscopy and analysis of the ν 1 band of osmium tetroxide

We present the first high‐resolution stimulated Raman study of osmium tetroxide (OsO 4 ). Lines from the ν 1 totally symmetric stretching fundamental have been assigned. These data together with the infrared assignments of the ν 3 band previously recorded (M. Louviot et al ., J. Quant. Spectrosc. Radiat. Transfer , 2012, 113, 119–127) allowed a refinement of the analysis of the ν 1 / ν 3 stretching dyad. We found that the ν 1 band has an unusual positive isotopic shift of approximately 0.32 cm − 1 /amu, which gives further evidence that the stretching dyad should be perturbed by a complex nearby bending band polyad. This work is part of a global effort to analyze all fundamental bands of OsO 4 to obtain a more precise experimental value of the ground state bond length for this heavy metal‐containing molecule. The result could serve as a benchmark for high‐level quantum chemistry calculations. Copyright © 2012 John Wiley & Sons, Ltd.