Peak-power dependence of rovibronic populations below the quasicontinuum during IR multiphoton absorption

• Main Author: Brenner, D M
• Other Authors: United States. Department of Energy.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Brookhaven National Laboratory 1981
• Subjects: Rotational States; Dissociation; Carbonic Acid Derivatives; Vibrational States; Absorption Spectroscopy; Laser Radiation; Organic Compounds; Phosgene; 74 Atomic And Molecular Physics; Mathematical Models; Infrared Radiation; Organic Halogen Compounds; Excited States; Molecules; Radiations; Spectroscopy 640304* > Atomic; Molecular & Chemical Physics > Collision Phenomena; Energy Levels; Organic Chlorine Compounds; Electromagnetic Radiation; Carbonic acid
• Online Access: https://digital.library.unt.edu/ark:/67531/metadc1210485/

Experimental studies on IR multiphoton absorption and dissociation have generally provided insight only into the relationship of IR laser characteristics such as power, wavelength, and mode structure to the observables dissociation yields, average number of photons absorbed, and product energy distribution. As a result, theoretical modeling of absorption at levels below the quasicontinuum has been based on facts somewhat removed from the actual phenomenon of interest. The experiments presented here provide information on the unperturbed rotational/vibrational populations of levels subsequent to IR excitation at levels below 4000 cm/sup -1/ of energy. The experiment makes use of molecular beam techniques in conjunction with IR-visible double resonance. A CO/sub 2/ laser of known pulse duration prepares vibrationally excited thiophosgene, Cl/sub 2/C = S. The absorbing transition is 2 .nu./sub 4/. A tunable nitrogen-pumped dye laser scans the visible excitation spectrum to probe the perturbed rotational-vibrational populations of the pumped mode. Because the electronic transition is electric dipole forbidden, combination hot bands having the appropriate quantum numbers of the ground state are used in the analysis.