Raman intensity with the electric vector of the scattered
electromagnetic radiation perpendicular to that of the incident radiation divided by the
Raman intensity with electric vectors parallel.
Note: In
normal Raman scattering with linearly polarized exciting radiation,
\(\rho \le 0.75\) for totally symmetric vibrations and
\(\rho = 0.75\) for all other vibrations.
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 743 (https://doi.org/10.1515/pac-2019-0203)