Molecular structure of the dye betaine 30 (dark contours) in the solvent dimethyl-sulfoxide (DMSO) (IMAGE)
Caption
Fig. 1. Molecular structure of the dye betaine 30 (dark contours) in the solvent dimethyl-sulfoxide (DMSO). The disordered dye molecules possess a permanent electric dipole moment along their longitudinal axis (white arrows). The interaction with the time-dependent THz electric field ETHz(t) changes the energy of the ground state S0 and the first excited state S1 of the molecules (level scheme bottom left) and, concomitantly, the frequency position of optical absorption. This spectral shift is mapped in real-time by an ultrashort probe pulse Iprobe(t). The sign and the amount of the spectral shift (spectra bottom right) depend on the spatial projection of the local THz electric field onto the molecular dipole direction. The experiment provides the temporal evolution of the absorption spectrum averaged over all dipole orientations.
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MBI/B. Fingerhut/J. Zhang
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