Eur. Phys. J. B 75, 187-195 (2010)
https://doi.org/10.1140/epjb/e2010-00135-1

Raman scattering for weakened bonds in the intermediate state: enhancement of low-frequency vibrations

¹ Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia
² Donostia International Physics Center, Paseo Manuel de Lardizàbal 4, 20018 Donostia, San Sebastian, Spain, and Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, 20125 Milano, Italy

Corresponding author: hizh@fi.tartu.ee

Received: 4 January 2010
Revised: 22 March 2010
Published online: 6 May 2010

Abstract

A multimode theory of the Raman scattering in resonance with an electronic transition causing a strong weakening of atomic bonds is proposed. Simple analytical relations between the Fourier transforms of the first- and second-order Raman amplitudes and the absorption are derived. It is predicted that the Raman scattering on low-frequency vibrations will be strongly enhanced. Besides the second-order Raman scattering is also enhanced as compared to the first-order scattering. The Raman excitation profiles show a structure caused by the Airy oscillations. The shapes of the profiles of all vibrations contributing to the weakening bond are the same as a consequence of the strong mode mixing under the virtual vibronic transition.