Vibrationally Excited Ions: Quenching Reaction Enhancement, Lifetimes
Abstract
During the course of studies at Aberystwyth of vibration al relaxation of hydrogen halide ions it was observed that the proton transfer reactions of HBr with both CH4 and CO2 are endothermic. This shows that a recently proposed upward revision of the proton affinity scale in the 120- 145kcal mol range is in error and indeed that the value of the proton affinity of CH4 P.A.(CH4) = 132 kcal mol in the National Bureau of Standards (NBS) tables (which are currently the most widely used references on proton affinities and thermochemical data) is somewhat too large. In order to quantify the proton affinity differences among BR, CH4 and CO2 the dependences on temperatures of the rate coefficients for endothermic proton transfer from HBr+ to CH4 and CO2 have been measured using the variable-temperature selected ion flow tube in Birmingham. The problem in determining values of proton affinity is in setting the absolute scale since most laboratory measurements yield only relative proton affinities, these usually being obtained from equilibrium constant measurements.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1991
- Accession Number
- ADA241852
Entities
People
- Lance Thomas
Organizations
- Aberystwyth University