Recording of infrared Raman-scattered light by conversion to the visible range

A theoretical analysis is made of a new method for recording infrared Raman-scattering radiation. The essence of the method lies in the mixing of the scattered radiation and of the pumping radiation in a nonlinear crystal and detecting the resultant sum frequency with a photomultiplier. It is shown that this method should ensure reliable recording even of the radiation resulting from the Raman scattering in gases.