Photon Energy Dependent Micro-Raman Spectroscopy with a Continuum Laser Source

We present a method for continuous, photon energy dependent micro Raman spectroscopy. A narrow excitation line is selected from a continuum laser by an acousto-optic tunable filter (AOTF) plus an additional monochromator (MC). Automation of laser, AOTF, MC and tunable long pass filters enables us to continuously scan the wavelength over the full visible range while synchronously acquiring Raman spectra over a photon energy range from 1.85 eV to 2.83 eV. We demonstrate the applicability of our method on a well-studied sample, reduced graphene oxide (rGO), where we measure the Raman scattering over the whole visual range and use the photon energy dependence of the D, G and GS band as verification for the method we present here. We complement this set of data with additional results from a Ti: sapphire laser source, covering the 1.75 to 1.41 eV range. From the full photon energy range of 1.41 to 2.83 eV, we noticed a small deviation from linearity for the dispersion of the D band.