Proton Quantum Confinement on Symmetric Dimers of Ammonia and Lower Amine Homologs

Abstract

Behavior of shared proton in symmetric dimers of ammonia and lower amine homologs were studied by several theoretical methods. Corresponding optimized structures by density functional theory show an intuitive hypsochromic shift as the degree of methylation is enhanced. Inclusion of nuclear quantum effect, however, changes the whole picture. It was found out that the fundamental vibrational transition corresponding to the shared proton’s stretching motion, νsp is counter intuitive. Based from these calculations, there is a bathochromic shift from ammonia to trimethylamine. These ramifications do clearly indicate that proton is a quantum object. Furthermore, spectroscopic features for the stretching modes of the shared proton and H-bond donor-acceptor atoms were proposed.