The sum-frequency generation involving two infrared laser quanta and a single visible-range laser quantum is a four-wave mixing process that is virtually not used in practice. Nevertheless, this process provides an extremely high selectivity with respect to the Q-branch of the two-photon vibrational transition in molecules. We explore here two publications, one that is more than thirty years old and another that appeared in 2018, to show broad potential applications of the method. The objective reasons due to which that potential has not been used so far are discussed.

Keywords: sum frequency generation, two-photon resonance, infrared spectroscopy of molecules PACS: 33.20.Ea, 42.62.Fi, 42.65.−k (all) DOI: 10.3367/UFNe.2018.12.038492 URL: https://ufn.ru/en/articles/2019/3/c/ 000469214700003 2-s2.0-85069429219 2019PhyU...62..257M Citation: Makarov A A, Ryabov E A "On a half-forgotten but very powerful method for coherent spectroscopy of molecules" Phys. Usp. 62 257–265 (2019) BibTexBibNote ® (generic)BibNote ® (RIS)MedlineRefWorks Received: 11th, July 2018, revised: 5th, December 2018, accepted: 6th, December 2018 Оригинал: Макаров А А, Рябов Е А «Об одном полузабытом, но весьма мощном методе когерентной спектроскопии молекул» УФН 189 271–280 (2019); DOI: 10.3367/UFNr.2018.12.038492