Two-photon excitation of the D 1Δ–X 1Σ+ transition in carbon monoxide

Abstract
A frequency doubled pulsed dye laser is used to promote two‐photon excitation of the D1Δ−X1Σ+ transition in carbon monoxide. Collisional transfer to A1Π leads to ultraviolet fluorescence which is detected with a solar blind photomultiplier. Rotationally resolved structure belonging to bands of three isotopically substituted molecules has been measured relative to the visible spectrum of iodine. Preliminary values of molecular constants are given.