Infrared Emission And Absorption Studies Of Polyatomic Photodissociation Dynamics

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Download or read book Dynamics of Infrared Multiphoton Dissociation of SF6 by Molecular Beam Method. [Nonrandomize Excitation Energy]. written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The decomposition of polyatomic molecules by infrared multiphoton absorption is a subject which is under extensive investigation in many laboratories. The process has been shown to be efficient, selective and collisionless. The physical principles which are mainly responsible for the absorption of a large number of photons by an isolated molecule under intense infrared laser radiation have been elucidated through many experimental and theoretical investigations. However, one very important question which remains to be answered is the relation between the dynamics of molecular decomposition and the degree of vibrational excitation, i.e., the question of whether the excitation energy is completely randomized before molecular decomposition. The production of electronically excited fragments in the dissociation of halogenated hydrocarbons and the observations of SF4 fragment in the decomposition of SF6 without the evidence of the formation of lower energy SF5 fragment provided some basis of speculation that the excitation energy might not be randomized before the dissociation of excited molecules. A crossed molecular beam apparatus has been adapted to study the dynamics of excitation and dissociation of polyatomic molecules in intense IR laser fields. Initial experiments have involved the study of the dissociation of SF6 by CO2 laser radiation at 10.6 .mu.m. a molecular beam of SF6 was formed by supersonic expansion using three stages of differential pumping. A grating tuned pulsed CO2 TEA laser was used as the excitation source. The laser beam was focused by a 25 cm focal length ZnSe lens, and crossed the molecular beam near its focal point. The fragments produced by multiphoton dissociation of SF6 within the small interaction region were detected as a function of recoil angle and velocity.