Determination of the Resolution of a Multichannel Raman Spectrometer Using Fourier Transform Raman Spectra

Abstract

The resolution of a grating polychromator for Raman spectroscopy has been simulated by measuring spectra on a Fourier transform (FT) Raman spectrometer and selecting the FT of the apodization function so that the instrument line shape function mimics the triangular spectral slit function of the polychromator. To this end, FT-Raman spectra measured with a nominal resolution of 0.5 cm⁻¹ were modified through the application of sinc² apodization functions of various widths to simulate spectra measured on a polychromator at lower resolution. The success of this approach was validated using the 1085 cm⁻¹ band of calcite. When the modified FT-Raman spectra were compared with spectra measured on a grating polychromator equipped with slits of widths 100 and 150 μm, the resolution of the polychromator was estimated to be 6.3 and 7.8 cm⁻¹, respectively. This conclusion was verified experimentally by measuring the separation of two bands in the Raman spectrum of BaSO₄ at ∼460 cm⁻¹