Picosecond Emission Spectroscopy of Homogeneously Broadened, Electronically Excited Molecular States

We present a direct observation of an ultrafast time-resolved emission spectrum of a dye molecule in solution, the time resolution of the system being 2 × ${10}^{-12\mathrm{}}$ sec. Vibrational relaxation within the vibrational manifold of the excited electronic state of rhodamine 6G occurs within 6 × ${10}^{-12\mathrm{}}$ sec. We discuss the implications of these results for the understanding of homogeneous broadening of excited electronic states of large molecules.