Hydrogen Bond: An Experimental Verification of the Double Minimum Potential

Abstract
The spectra of alcohols in the region of the first and second OH stretching overtone in solvents of various bonding strengths reveal a pair of solvent dependent absorption bands. These bands are shown to arise from an energy level splitting resulting from a double minimum in the potential energy curve for the proton. The form that the potential energy curve must assume to yield the observed spectra is such that the second minimum lies in the region of the v=2 vibrational energy level for ordinary hydrogen bonding situations. The higher overtone bands, particularly in strongly basic solvents, are characteristic of the broad potential well. This observed splitting of the absorption bands of hydrogen bonded alcohols confirms the theoretical predictions of a double minimum potential energy function for the proton.