Infrared Laser-Induced Isotope-Selective Dissociation of Molecular van der Waals (SF6)mArn Clusters

Abstract

The results of studies on the isotope-selective dissociation of homogeneous and mixed van der Waals (SF6)mArn clusters induced by infrared laser radiation are presented. The method is based on the selective vibrational excitation of clusters by an infrared laser, which leads to their heating and dissociation. An experimental setup and procedure are described. The results of measurements of the efficiency and selectivity of cluster dissociation at different pressures and gas compositions above the nozzle, as well as various parameters of laser radiation, are presented. The dependences of the efficiency and selectivity of cluster dissociation on the frequency and power of the exciting laser radiation on the composition and pressure of gas above the nozzle, as well as on the distance of the irradiation zone of the particles on the nozzle exit are obtained. It is shown that the frequency of laser radiation and the composition and pressure of gas above the nozzle significantly affect the parameters of selective infrared dissociation of clusters. Experiments on isotope-selective dissociation of both homogeneous (SF6)m clusters and mixed (SF6)mArn clusters are performed. It was found that, with the dissociation of (SF6)mArn clusters, a rather high selectivity can be reached. Thus, in the case of an SF6/Ar mixture at a pressure ratio of 1/200, for the selectivity of dissociation of (32SF6)2 clusters with respect to $$^{{34}}{\text{SF}}_{6}^{{32}}$$ SF6 clusters, the values ≥10–20 are obtained under conditions of irradiation by a beam on the 10P(32) laser line (at a frequency of 932.96 cm–1). Conditions are found when the values of efficiency and selectivity of dissociation of homogeneous (SF6)m clusters and mixed (SF6)mArn clusters are optimal.