Scanning cavity-enhanced droplet spectroscopy: Tuning of the excitation laser for obtaining a continuous Raman spectrum

Scanning cavity-enhanced droplet spectroscopy (S-CEDS) has been developed to obtain Raman spectra of liquid media with high sensitivity. Cavity-enhanced Raman spectra of a water droplet are measured by irradiation of a laser with nine different wavelengths. Each of the spectra consists of a series of intense and narrow peaks resulting from the cavity-enhancement conditions, and the envelope of their peak apexes displays a stimulated Raman spectrum of liquid water. A series of continuous Raman spectra of liquid water is obtained by scanning the laser wavelength, which dissolves the discreteness of each spectrum. S-CEDS provides a novel method to obtain stimulated Raman spectra of liquid media keeping their continuous spectral shapes.