A spectrometer for high-resolution and high-contrast Brillouin spectroscopy in the ultraviolet

We present a multiple-grating spectrometer designed for high-resolution and high-contrast low-frequency scattering spectroscopy in the ultraviolet, as well as in the visible spectral regions. The instrument has a resolution better than 1 GHz and a contrast of about 1×10−10 both in the visible and in the UV range, thus doubling the highest resolution achieved by double-monochromator double-pass spectrometers such as the SOPRA DMDP2000, conceived for Raman–Brillouin spectroscopy using visible excitation. Performance tests and the Brillouin spectra obtained in the ultraviolet range are reported. Ray tracing results, aiming to give a better insight on the instrument performances are also presented. The instrument opens the possibility to study a new region of the exchanged momentum with a suitable energy resolution and to investigate the spectrum of density fluctuations in materials where the UV penetration depth could be a relevant step for the experimental study of the dynamics of disordered material.