Vibrational relaxation and energy transfer in the hydrogen system at temperatures between 110 and 300 K

Abstract

The collisional relaxation and vibrational energy transfer of vibrationally excited hydrogen H 2( v″=1) has been investigated in a low-pressure (5.33 hPa) Teflon-coated fast-flow (17 m s −1) reactor in the temperature 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 monitored along the flow tube axis via Q-branch transitions using vibrational coherent anti-Stokes Raman spectroscopy (CARS). Wall deactivation probabilities and thermal rate constants for the vibrational energy transfer in collisions with D 2( v″=0) were determined as a function of temperature from a direct comparison of measured concentration profiles with results from computational modeling of the reactive flow using a numerical flow code with appropriate chemical kinetics. Results are compared with experiments and theoretical models from the literature.