Selective obliteration of SF6 molecules based on multiphoton absorption

The selective multiphoton excitation of vibrotational states of ³²SF₆ species has been done by a pulsed CO₂ laser tuned at 948 cm^-1. The Littrow grating arrangement with 100 lines/mm, 22° blazing angle is used to assure the laser bandwidth to be adequately less than the SF₆ isotope shifts (17 cm^-1). The subsequent molecular dissociation occurs at high power densities. A FTIR spectrometer with 4 cm^-1 resolution is employed to register characteristic peaks of ³²SF₆ and ³⁴SF₆ at 948 and 931 cm^-1 respectively. The dissociation rate strongly decreases at higher pressures due to rapid deactivation of excited molecules based on momentum transfer of vibrational-translational process by collisional events between ³²SF₆ and buffer molecules. Moreover the selectivity decreases at higher pressures, which mainly arises from vibrational-vibrational excitations of pertinent collisions among species to cause resonant obliteration of ³⁴SF₆ molecules, consequently.