A method is described for eliminating the Doppler effect by the counterpropagating-beam two-photon technique. Emphasis is placed on gas-phase molecular electronic-state spectroscopy. Past accomplishments with this method are summarized and applications of the method are discussed.
Jerry A. Gelbwachs,
John E. Wessel,
"Doppler-Free Two-Photon Spectroscopy Applied to Molecular Electronic Transitions," Optical Engineering 16(2), 162197 (1 April 1977). https://doi.org/10.1117/12.7972099