The Raman effect and its application to electronic spectroscopies in metal-centered species: Techniques and investigations in ground and excited states

In the decades since its discovery and somewhat limited early applications, Raman scattering has become the basis for the development of a variety of methods for probing molecular structure both in ground and electronically excited states. In this review, following a brief look at the underlying principles of the Raman and resonance Raman effects, the intention is to discuss a range of Raman techniques, especially in the context of their application to metal-centered systems. The review will focus on molecular electronic spectra, including bioinorganic examples, and on dynamic processes following electronic excitation. Methods to be surveyed will include continuous wave resonance Raman, surface-enhanced resonance Raman, time-resolved Raman and resonance Raman spectroscopies, which are used to probe the excited state processes, including vibrational dynamics, observed in molecular systems. The review will also include reference to coherent anti-Stokes Raman scattering, femtosecond coherent vibrational spectroscopy and time-resolved stimulated Raman spectroscopy on the femtosecond timescale.