VIBRATIONAL-RELAXATION AND ENERGY-TRANSFER IN THE HYDROGEN SYSTEM AT TEMPERATURES BETWEEN 110 AND 300 K

The collisional relaxation and vibrational energy transfer of vibratio nally excited hydrogen H-2(nu ''=1) has been investigated in a low-pre ssure (5.33 hPa) Teflon-coated fast-flow (17 m s(-1)) reactor in the t emperature range 110 K < T< 300 K. Vibrationally excited hydrogen was produced through microwave discharges prior to mixing with helium or D -2. Relative concentration distributions of hydrogen species were moni tored along the flow tube axis via Q-branch transitions using vibratio nal coherent anti-Stokes Raman spectroscopy (CARS). Wall deactivation probabilities and thermal rate constants for the vibrational energy tr ansfer in collisions with D-2(nu '' = 0) were determined as a function of temperature from a direct comparison of measured concentration pro files with results from computational modeling of the reactive flow us ing a numerical flow code with appropriate chemical kinetics. Results are compared with experiments and theoretical models from the literatu re. (C) 1998 Published by Elsevier Science B.V. All rights reserved.