Spectroscopic observation of the forward and backward IR emission of bacteriorhodopsin under broadband optical pumping

Abstract

Abstract For the first time, it was demonstrated that the secondary IR emission stimulated by visible light propagates not only in the direction opposite to the exciting beam, but also in the forward direction. Furthermore, by a control of the forward-directed beam arrival back at the sample time- picosecond resolution was achieved. Using the forward-directed beam as a probe beam, we were able to obtain additional information about the properties of the bacteriorhodopsin in the excited state. The performed studies open the possibility for analyzing the molecular excitation, vibrational coupling, and relaxation processes directly during electronic excitation in picoseconds time scales.