Hole burning spectroscopy ground state

The very first fluorescence spectra of jet-cooled exciplexes indicated the existence of two types of ground-state van der Waals adducts. For instance, the anthracene-dimethylaniline system displayed two types of cluster bands in the fluorescence excitation spectrum broad ( 150 cm ) and structureless, leading to typical ex-ciplex emission, and narrow (1 cm ), leading to resonance-type emission [10, 20]. It was assumed that they are due to different 1 1 adducts, distinguished by different geometries. Recently, laser-based techniques were developed that allow the discrimination of different species. One is hole-burning spectroscopy and another— mass-selected photoionization. 

In hole-burning spectroscopy, on the other hand, the bum laser frequency is fixed while the probe laser frequency is tuned. The pump laser depletes the ground state of a single conformation, so that the probe laser records an excitation spectmm of all conformers except the one selected by the bum laser. It should be noted that in both cases the hot bands are not affected, because only the ground state is depopulated. In addition, for both methods to be effective, the bum laser pulse energy should be sufficient to induce a substantial ground state depletion. 

We have adopted the excitonic band model not only because it describes conventional absorption spectroscopy (linear spectroscopy), but because it enables an extremely convenient description of nonlinear experiments, such as pump-probe, dynamical hole burning, or photon echoes. In these third-order experiments one has to consider not only transitions from the ground state to the one-excitonic states but also transitions from the one-excitonic to the two-excitonic states (see Fig. 13). These additional transitions reveal the required information to deduce, at least in principle, the complete coupling scheme. 

Schmitt, M Muller, H., Henrichs, U., Gerhards, M., Perl, W., Deusen, C., and Kleinermanns, K Structure and vibrations of phenol-CH(CDjOD) in the electronic ground and excited state, revealed by spectral hole burning and dispersed fluorescence spectroscopy, J. Chem. Phys. 103, 584-594 (1995). 

Fig. 3 a) mass selected one-color REMPI spectrum, b) IR-UV ion dip spectra, and c) IR-UV hole-bum spectra of the capped dlpeptide PheCys adapted from 8] The REMPI spectmm shows the vibrational progression of the electronic excited state of multiple conformations. The contributions of these conformers are visualized using the conformer selective IR-UV hole-burning method. The structure of the individual conformers can be probed by IR-UV ion-dip spectroscopy, yielding conformer specific ground-state IR spectra. 

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