Piwoński, Hubert; Stupperich, Clemens; Hartschuh, Achim; Sepioł, Jerzy; Meixner, Alfred Johann; Waluk, Jacek (2005): Imaging of Tautomerism in a Single Molecule. In: Journal of the American Chemical Society, Vol. 127, Nr. 15: S. 5302-5303




Fluorescence imaging is used to visualize directly the transfer of two inner hydrogen atoms in single porphycene molecules. This reaction leads to a chemically equivalent but differently oriented structure and hence results in a rotation of the transition dipole moments. By probing single immobilized molecules with an azimuthally polarized laser beam in the focal spot of a confocal microscope we observe ring-like emission patterns, possible only for a chromophore with two nearly orthogonal transition dipole moments. Numerical simulations of the observed emission patterns yield a value of 72° for the angle between the S0−S1 transition moments in the two tautomeric forms.