Vibronic excitation of single molecules: a new technique for studying low-temperature dynamics.
Herein, we present vibronic excitation and detection of purely electronic zero-phonon lines (ZPL) of single molecules as a new tool for investigating dynamics at cryogenic temperatures. Applications of this technique to study crystalline and amorphous matrix materials are presented. In the crystalline environment, spectrally stable ZPLs are observed at moderate excitation powers. By contrast, investigations at higher excitation intensities reveal the opening of local degrees of freedom and spectral jumps, which we interpret as the observation of elementary steps in the melting of a crystal. We compare these results to spectral single-molecule trajectories recorded in a polymer. The way in which much more complicated spectral features can be analysed is shown. Surprisingly, pronounced spectral shifts on a previously not accessible large energy scale are observed, which are hard to reconcile with the standard two-level model system used to describe low-temperature dynamics in disordered systems.
Kiraz
Alper
A
Department Chemie und Biochemie and Center for NanoScience, Ludwig-Maximilians Universität München, Butenandtstr. 11, 81377 München, Germany.
Ehrl
Moritz
M
Hellriegel
Christian
C
Bräuchle
Christoph
C
Zumbusch
Andreas
A