Raman and site selection fluorescence spectra are compared when these spectra have been measured with conventional fixed wavelength excitation and with modulated wavelength excitation. The samples were solutions of benzene and of chlorophyll. The modulated wavelength method records the differential spectra. Simple analysis of signal/noise ratios from these different experimental techniques show modulation methods can give improvements under particular conditions. These conditions are discussed.
J. Funfschilling and D. F. Williams, "CW Laser Wavelength Modulation in Raman and Site Selection Fluorescence Spectroscopy," Appl. Spectrosc. 30, 443-446 (1976)