sum-frequency generation spectroscopy electronic sum-frequency generation spectroscopy https://orcid.org/0000-0001-5985-7429 ESFG spectroscopy A method for generating surface-specific electronic spectra by mixing two light beams at a surface and detecting the output beam, which has frequency equal to the sum of the two input frequencies. electronic sum-frequency generation (ESFG) spectroscopy CHMO:0002675 electronic sum frequency generation spectroscopy 2010-01-13T04:01:47Z