Multiphoton dissociation of formic acid molecules under action of free electron laser

The successful experiments on the isotopic-selective infra-red multiphoton dissociation (IR MPD) of the formic acid molecules have been performed with the radiation of a free electron laser (FEL) for the first time. Upon irradiating the H12COOH + H13COOH (50% + 50%) mixture in the spectral region of the C=O stretch vibrational band in the dissociation product CO either 13C or 12C isotope predominates that depends on the laser radiation frequency. In the sample with the natural isotopic content the enrichment of CO by the 13C isotopic has been attained 19.5% compared with 1.1% of natural content. Also the about fivefold enrichment of CO by the 18O isotope has been observed.