Highly selective and efficient multiphoton dissociation of polyatomic molecules in multiple-frequency IR-laser fields

Abstract

An ir multiphoton dissociation (MPD) process in multiple-frequency ir-laser fields has been experimentally realized. A selectivity ofS=104 was obtained in separating13C/12C isotopes upon multiple-frequency ir multiphoton dissociation (MFMPD) of the CF2HCl molecule, the dissociation yield13β for the13CF2HCl molecule amounting to around 1%. A yield of13β was reached at a selectivity ofS=102, and the total laser fluence required for the process was reduced. A new mechanism—“sticking” of molecules on the lower discrete vibrational levels—responsible for the low MPD yields observed for some molecules is discussed and a technique to eliminate it and thus maximize the dissociation yields is proposed. Ways to improve the selectivity by MFMPD are analyzed and a simple method for obtaining from a single TEA CO2 laser a multiple-frequency radiation suitable for experimental realization of MFMPD is suggested.