# MEASUREMENT OF ROTATIONAL STATE-TO-STATE RELAXATION COEFFICIENTS BY RAMAN-RAMAN DOUBLE RESONANCE. APPLICATION TO SELF-COLLISIONS IN ACETYLENE.

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/38279

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 Title: MEASUREMENT OF ROTATIONAL STATE-TO-STATE RELAXATION COEFFICIENTS BY RAMAN-RAMAN DOUBLE RESONANCE. APPLICATION TO SELF-COLLISIONS IN ACETYLENE. Creators: Domenech, J. L.; Martinez, R. Z.; Bermejo, D. Issue Date: 2009 Publisher: Ohio State University Abstract: We have developed a technique for the measurement of state-to-state rotational relaxation rates due to collisions in the gas phase. A single J state of the $v_{2}=1$ vibrational level of acetylene is populated by a Stimulated Raman process. After a variable delay of a few ns we record high resolution ($\sim$ 0.003 cm$^{-1}$) spectra of the Q-branch of the $v_{2}=2\leftarrow v$_{2}=1$transition by a second Stimulated Raman process. The relative intensities of the lines of this Q-branch, recorded as a function of the the initially pumped J level and the number of collisions between the pump and probe stages (delay$\times\$ pressure product), allows us to obtain a set of state-to-state energy transfer coefficients by fitting the evolution of the observed populations to that predicted by a master equation with adjustable coefficients. The experimental details and first results for odd-J levels of acetylene at 150 K will be presented. Description: Author Institution: Instituto de Estructura de la Materia (CSIC), Serrano 123, E-28006 Madrid, SPAIN URI: http://hdl.handle.net/1811/38279 Other Identifiers: 2009-WG-11