Multiphoton isotope-selective dissociation of formic acid molecules under action of free electron laser

Successful experiments on isotope-selective infra-red multiphoton dissociation (IR MPD) of formic acid molecules have been performed with the radiation of a free electron laser (FEL) for the first time. Upon irradiating the (HCOOH)-C-12 + (HCOOH)-C-13 (50% + 50%) mixture in the spectral region of the C=O stretch vibrational band, the dissociation product CO has either C-13 or C-12 isotopes, which one is predominate depending on the laser radiation frequency. In the sample with the natural isotopic content the enrichment of CO by the C-13 isotope has been achieved at a level of 19.5% as compared to a 1.1% level of natural content. Also, a fivefold enrichment of CO by the O-18 isotope has been observed.