Determination of the absolute Raman cross‐sections of α‐S8 film at ultralow frequencies pumped by 488 and 785 nm lasers

Abstract

AbstractAbsolute Raman cross‐sections are widely used for quantitative analyses of condensed phases. However, solid thin films showing ultralow frequency (ULF) Raman characteristics at <100 cm−1 have not been studied deeply. Herein, we demonstrate an ULF Raman spectrometer equipped with 488 and 785 nm pumped lasers and determine the absolute Raman cross‐sections of 34‐μm‐thick α‐S8 film, which presents Raman peaks at approximately 27, 50, 83, 154, and 220 cm−1. These experimentally measured ultralow Raman frequencies and Raman cross‐sections were also confirmed via first principles density functional theory. Thus, our Raman cross‐section studies can be utilized as a quantitative standard for thin films showing ULF Raman characteristics.