Determination of dissociation energies and thermal functions of hydrogen‐bond formation using high resolution FTIR spectroscopy

A technique which employs high resolution Fourier transform infrared spectroscopy is demonstrated for evaluation of hydrogen bond dissociation energies D₀ and D_e. Results for HCN‐‐HF give a D₀=20.77(22) and D_e =28.77(45) kJ/mol which are compared with previously determined values obtained from microwave absolute intensity measurements and ab initio molecular orbital calculations. Rovibrational band information available for HCN‐‐HF also permits evaluation of thermal functions of dimer formation in kJ/mol: ΔU^○_298.2 =20.1(2), ΔH^○_298.2 =22.6(2), ΔG^○_298.2 =59.4(2), ΔS^○_298.2 =−0.1235.