Lineshape analysis of coherent multidimensional optical spectroscopy using incoherent light

Coherent two-dimensional electronic spectroscopy using incoherent (noisy) light, I⁽⁴⁾ 2D ES, holds intriguing challenges and opportunities. One challenge is to determine how I⁽⁴⁾ 2D ES compares to femtosecond 2D ES. Here, we merge the sophisticated energy-gap Hamiltonian formalism that is often used to model femtosecond 2D ES with the factorized time-correlation formalism that is needed to describe I⁽⁴⁾ 2D ES. The analysis reveals that in certain cases the energy-gap Hamiltonian is insufficient to model the spectroscopic technique correctly. The results using a modified energy-gap Hamiltonian show that I⁽⁴⁾ 2D ES can reveal detailed lineshape information, but, contrary to prior reports, does not reveal dynamics during the waiting time.