ABSTRACT
In Chapter 4, a response function theory for general second-order response spectroscopy was presented and discussed. Here, it will be shown that they can be used as 2D measurement techniques. An essential element for 2D spectroscopy is that radiation-matter interactions cause doubly resonant transitions, and two coherence evolutions should be recorded experimentally. Thus measured 2D signal in timedomain is then doubly Fourier-Laplace transformed to obtain the corresponding 2D spectrum in frequency domain. The second-order response measurement techniques such as time-resolved doubly resonant sum frequency generation, fifth-order Raman scattering, IR-IR-vis four-wave-mixing spectroscopy, and so forth are a few examples that will be considered in this chapter. Note that they all involve two coherence evolutions during the nonlinear optical processes.
