Fourier Transform Raman Spectroscopy of Long-Chain Molecules Containing Strongly Absorbing Chromophores

TLDR

Fourier transform Raman spectroscopy is a promising technique for molecules with visible‑absorbing chromophores, offering advantages that could be realized if routine data collection matches the complexity of conventional Raman scattering. The study implemented a 90° scattering geometry in FT‑Raman measurements to evaluate its performance relative to the conventional 180° reflective optics setup. Using near‑infrared excitation, the authors obtained fluorescence‑free spectra and compared FT‑Raman results for liquids and solids with conventional scanning Raman measurements. The 90° geometry produced spectra comparable to the 180° reflective optics, and FT‑Raman measurements of liquids and solids matched conventional scanning Raman results.

Abstract

Fourier transform Raman spectroscopy shows considerable promise as a new characterization technique for molecules which contain chromophores which absorb in the visible region, the region where conventional Raman measurements are made. With the use of near-infrared excitation, spectra in the absence of fluorescence and resonance enhancement are obtained. These advantages can be further enhanced if the collection of data using this technique becomes routine, requiring a level of complexity comparable to that of conventional Raman scattering. Toward that end, the implementation of a 90° scattering geometry in our FT-Raman measurements was undertaken, and the results are shown to be at least comparable to those obtained with the use of reflective optics in a 180° geometry. A number of results on both liquids and solids have also been obtained in order to compare FT-Raman with conventional scanning Raman measurements.