A theory for the calculation of resonant
and nonresonant hole-burning
(HB) spectra of pigment–protein complexes is presented and
applied to the water-soluble chlorophyll-binding protein (WSCP) from
cauliflower. The theory is based on a non-Markovian line shape theory
(RengerMarcusRengerMarcusJ. Chem. Phys.20021169997) and includes exciton delocalization, vibrational
sidebands, and lifetime broadening. An earlier approach by Reppert
(J. Phys. Chem. Lett.201122716) is found to describe nonresonant HB spectra only. Here we present
a theory that can be used for a quantitative description of HB data
for both nonresonant and resonant burning conditions. We find that
it is important to take into account the excess energy of the excitation
in the HB process. Whereas excitation of the zero-phonon transition
of the lowest exciton state, that is, resonant burning allows the
protein to access only its conformational substates in the neighborhood
of the preburn state, any higher excitation gives the protein full
access to all conformations present in the original inhomogeneous
ensemble. Application of the theory to recombinant WSCP from cauliflower,
reconstituted with chlorophyll a or chlorophyll b, gives excellent agreement with experimental data by Pieper
et al. (21417356J. Phys. Chem. B20111154053) and allows us to obtain an upper bound of the lifetime of the upper
exciton state directly from the HB experiments in agreement with lifetimes
measured recently in time domain 2D experiments by Alster et al. (24627983J. Phys. Chem. B20141183524).