In a recent report sum-frequency excitation of a Raman-active phonon was experimentally demonstrated for the first time. This mechanism is the sibling of impulsive stimulated Raman scattering, in which difference-frequency components of a light field excite a Raman-active mode. Here we propose that ionic Raman scattering analogously has a sum-frequency counterpart. We compare the four Raman mechanisms, photonic and ionic difference- and sum-frequency excitation, for three different example materials using a generalized oscillator model for which we calculate the parameters with density functional theory. Sum-frequency ionic Raman scattering completes the toolkit for controlling materials properties by means of selective excitation of lattice vibrations.
@article{arxiv.1801.05987,
title = {Sum-frequency ionic Raman scattering},
author = {Dominik M. Juraschek and Sebastian F. Maehrlein},
journal= {arXiv preprint arXiv:1801.05987},
year = {2018}
}