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

The collisional relaxation and vibrational energy transfer of vibrationally excited hydrogen H2(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 D2. 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 D2(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.