The occurrence of non-Gaussian spectral line shapes of molecules in electrostatically disordered media

We calculate the effects of relatively strong electric fields, correspondin g to typical values for the fields inside glasses and proteins, on the spec troscopic properties of a simple two-level molecule. Disorder in the electr ic field strength is employed as a physical source for inhomogeneous broade ning. A striking result is that a Gaussian probability distribution for, th e field over the ensemble does not give rise to a Gaussian spectral line sh ape. The results are used. to describe the absorption spectra of the B800 b and of the B800-850 light-harvesting complex of photosynthetic purple bacte ria.