Generalized magic angle for time-resolved spectroscopy with laser pulses of arbitrary ellipticity

Abstract

We present a general approach for calculating the magic-angle condition for time-resolved spectroscopy of isotropic samples. Allowing for arbitrary static polarizations and propagation directions of each pulse enables us to retrieve not only the known magic-angle conditions for linear and circular polarization, but also analogous conditions for anisotropy-free spectroscopy using elliptically polarized laser pulses. The results are exemplified on transient absorption and transferred to coherent two-dimensional spectroscopy. Furthermore we derive for transient absorption spectroscopy the relation between the measurable anisotropy and the molecular structure, i.e., the angle between the pumped and probed transition dipole moments (TDMs). The impact of multiple spectrally overlapping signals is considered and discussed on the example of a molecule with a two-fold degenerate TDM.