Absolute Raman frequency measurement of the Q(2) line in D_2 using cw CARS

Abstract
Coherent anti-Stokes Raman spectroscopy (CARS) is combined with high-resolution interferometry to measure the absolute Raman shift of the Q(2) vibrational line in D2. The preliminary value found is 2987.2371 ± 0.001 cm−1. Such precision is essential for the testing of ab initio energy-level calculations for the hydrogen isotopes.