Ultrafast fluorescence spectroscopy of photoactive yellow protein

Using the optical Kerr shutter method, room temperature time-resolved fluorescence spectroscopy of photoactive yellow protein (PYP) has been performed. Spectral profiles of the time dependent fluorescence have been measured as snapshots with high time resolution of about 300 fs. For the first time, spectral narrowing in the ps-time region was directly observed, which is consistent with the previously reported results of the faster decay on both sides of the fluorescence peak.