Stimulated Raman spectroscopy of excited vibrational states of the hydrogen molecule

A method for making direct measurements of the difference between the anharmonicities of the hydrogen molecule is proposed and implemented. It gives [$\mu\{Q_{01}\}(1)\}-\mu\{Q_{12}(1)\}]-[\mu\{Q_{12}\}(1)\}-\mu\{Q_{23}(1)\}]=4,837\pm 0,001$ cm$^{-1}$ if the reference lines are components of the complex spectrum of four-photon parametric light scattering accompanying stimulated Raman scattering due to the $Q_{01}(1)$, $Q_{12}(1)$, and $Q_{23}(1)$ transitions. The measured anharmonicity difference can be used to calculate the frequency of the $Q_{03}(1)$ transition in the hydrogen molecule reduced to zero gas density: $\mu\{Q_{03}(1)\} =11765,003\pm 0,001$ cm$^{-1}$.