Initial vibrational energy distributions determined by infrared chemiluminescence: the D/F2system

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Abstract
The measured relaxation infrared chemiluminescence method has been used to determine the relative primary rate constants for formation of deuterium fluoride in vibrational levels v′ = 2 to 12, and to show that the most populated level is v′ = 10. These results lead to a figure of 62 per cent for the fraction of available energy initially entering vibration. This value is approximately 5 per cent higher than the corresponding result for the H/F2 system. The deuterium fluoride energy distribution is in conflict with various previous calculations. New trajectory calculations using the LEPS surface previously found to be most appropriate for the H/F2 system suggest the v′ = 9 should be the most populated level. It was found that adjustment of the Sato parameters of this surface led to an improvement in the agreement between experimental and calculated distributions. However, use of this modified surface for the H/F2 reaction did not give as good a fit with the experimental vibrational distribution as that used previously. This finding, that a common LEPS surface did not lead to the best description of both the H/F2 and D/F2 cases, is suggested as being due to a limitation of the classical trajectory method.