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Imaging of Tautomerism in a Single Molecule

2005; American Chemical Society; Volume: 127; Issue: 15 Linguagem: Inglês

10.1021/ja043265c

1943-2984

Hubert Piwoński, Clemens Stupperich, Achim Hartschuh, Jerzy Sepioł, Alfred J. Meixner, Jacek Waluk,

Spectroscopy and Quantum Chemical Studies

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 degrees for the angle between the S0-S1 transition moments in the two tautomeric forms.