A Rayleigh-Brillouin scattering spectrometer for ultraviolet wavelengths

TL;DR

This paper introduces a specialized ultraviolet Rayleigh-Brillouin scattering spectrometer capable of high-resolution measurements of gas molecules, enabling detailed analysis of scattering profiles at various pressures and temperatures.

Contribution

The development of a high-power, narrow-bandwidth UV spectrometer with a unique scattering cell and Fabry-Perot analyzer for precise gas scattering measurements is presented.

Findings

High signal-to-noise ratio achieved at 1% level

Effective measurements on N2 and SF6 gases

Operates across 0-4 bar pressure and -30 to 70°C temperature range

Abstract

A spectrometer for the measurement of spontaneous Rayleigh-Brillouin scattering line profiles at ultraviolet wavelengths from gas phase molecules has been developed, employing a high-power frequency-stabilized UV laser with narrow bandwidth (2 MHz). The UV light from a frequency-doubled titanium:sapphire laser is further amplified in an enhancement cavity, delivering a 5 Watt UV-beam propagating through the interaction region inside a scattering cell. The design of the RB-scattering cell allows for measurements at gas pressures in the range 0-4 bar and at stably controlled temperatures from -30 to 70 degree Celsius. A scannable Fabry-Perot analyzer with instrument resolution of 232 MHz probes the Rayleigh-Brillouin profiles. Measurements on N2 and SF6 gases demonstrate the high signal-to-noise ratio achievable with the instrument, at the 1% level at the peak amplitude of the scattering profile.