The Theory of Surface Enhanced Hyper Raman Scattering

TL;DR

This paper develops a detailed Dipole-Quadrupole theory for Surface Enhanced Hyper Raman Scattering, explaining electromagnetic field behavior on rough metal surfaces and matching experimental spectra with theoretical predictions.

Contribution

The authors present a comprehensive Dipole-Quadrupole theoretical framework for SEHRS, including new expressions for cross-sections and selection rules, validated by experimental spectra analysis.

Findings

Enhanced dipole and quadrupole interactions near high-curvature surface regions.

Derived expressions for SEHRS cross-sections of symmetrical molecules.

Experimental spectra of pyrazine and phenazine align with the theoretical predictions.

Abstract

The Dipole-Quadrupole theory of Surface Enhanced Hyper Raman Scattering (SEHRS), created by the authors is expounded in details. Peculiarities of the behavior of electromagnetic field on rough metal surfaces are considered. It is demonstrated that there is an enhancement of the dipole and quadrupole light-molecule interaction near the places with a large curvature. The expression for the SEHRS cross-section of symmetrical molecules, which consists of several contributions is obtained. Selection rules for the scattering contributions are obtained and a qualitative classification of the contributions after an enhancement degree is performed. Analysis of experimental spectra of pyrazine and phenazine, and also some another molecules is performed too. It is demonstrated a full coincidence of experimental regularities in these spectra with the theory suggested.