Inelastic channel spectroscopy

Vibrational spectroscopy is based on two fundamental processes excitation and detection. As we shall see later in this chapter, they are not equivalent, and indeed both have to be treated to understand the origin of active modes in the spectra. The excitation is based on inelastic scattering processes, thus connecting initial and final states with different energy. The detection relies on the effect of the new inelastic channel on experimentally observable magnitudes, i.e. the junction conductance. 

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