Extreme UV absorption spectroscopy of CO isotopomers in pulsed supersonic free jet expansions

A supersonic pulsed jet for high-resolution studies of rotationally cold molecules was constructed at the 10.6 m vacuum UV spectrograph of the Observatoire de Meudon. The background continuum for photographic absorption work is emitted from a pulsedBalloffet–Romand–Vodar (BRV) source (vacuum spark). The new apparatus has been used to record the absorption spectra of the four main isotopomers of CO from 880 to 1110 Å (1 Å = 10−10 m). First results of the analysis help to clarify the rovibronic structure in two specific regions of the spectrum (103 000–103 300 and 109 300–109 600 cm−1) and are relevant to the discussion of 1Σ+–1Σ+ and 1Π–1Π homogeneous interactions of CO.