Multidimensional optical spectroscopy of a single molecule in a current-carrying state

Abstract

The nonlinear optical signals from an open system consisting of a molecule connected to metallic leads, in response to a sequence of impulsive pulses, are calculated using a superoperator formalism. Two detection schemes are considered: coherent stimulated emission and incoherent fluorescence. The two provide similar but not identical information. The necessary superoperator correlation functions are evaluated either by converting them to ordinary (Hilbert space) operators which are then expanded in many-body states, or by using Wicks theorem for superoperators to factorize them into nonequilibrium two point Greens functions. As an example we discuss a stimulated Raman process that shows resonances involving two different charge states of the molecule in the same signal. © 2010 American Institute of Physics.