F + H2, D2, HD reactions: Chemical laser determination of the product vibrational state populations and the F + HD intramolecular kinetic isotope effect

Abstract

Relative gain coefficients of individual HF^†(DF^†) laser transitions in the F + H₂, D₂, HD chemical lasers have been measured by a grating selection technique. Product vibrational population inversions N_ν/N_ν−1 were calculated from these measurements. The results indicate a complete parallelism in product vibrational energy content in the four room‐temperature isotopic reactions, modified only by a threshold effect for HF^†(ν = 3) production in the F + HD reaction and by secondary mass effects in the HF‐producing VS DF‐producing reactions. A room‐temperature measurement of the intramolecular kinetic isotope effect in the F + HD reaction is reported. Lastly, evidence is presented for highly efficient energy‐transfer processes [V → V′: HF^†(ν = 3) + HD(ν = 0) → HF^†(ν = 2) + HD^†(ν = 1) and E → V: I*(5 ²P_1/2) + HF^†(ν) → I(5 ²P_3/2) + HF^†(ν + 2)].