Application of liquid-core optical fiber in the measurements of Fourier transform Raman spectra

Abstract

The application of liquid-core optical fiber (LCOF) in the measurement of Fourier transform Raman spectra (FTRS) can enhance the Raman spectra intensity 10 2–10 3 times, and the minimal length of the optical fiber for yielding maximal Raman spectra intensity is the reciprocal of the optical fiber loss coefficient. By using LCOF, β-carotene's 1520 cm −1 Raman line and rhodamine's 1524 cm −1 Raman line were observed in their CS 2 solutions. These two Raman lines come from the π– π ∗ transition of the CC vibration. As β-carotene and rhodamine's concentrations decrease, their Raman lines move to long wavelength (red shift), their linewidths narrow and their molar gain coefficients increase.