Infra-Red Spectra of Hydrogen Bonded Systems: Theory and Experiment

Infra-red spectroscopy of hydrogen bonded systems is shortly reviewed. Both experimental and theoretical aspects of the problem are covered, but the accent is put on the theory. The first part of the paper refers to the classical, whereas its second part covers the time-resolved spectroscopy of the OH stretching band. Modern theories of vibrational band shapes are presented; they are all based on the density matrix approach of statistical mechanics and employ the correlation function formalism. Using this technique, molecular dynamics of hydrogen bonds can be monitored up to time scales of the order of a few tens of femtoseconds.