Intrinsic conformer jumps observed by single molecule spectroscopy in real time

Single molecule spectral dynamics originate from changes (1) within the chromophore and (2) in the chromophoric environment, hence are intrinsic and extrinsic. To interpret spectral phenomena of intrinsic origin, assignment of fluorescence behaviour to distinct molecular states is required. We realized this by means of a perylene based chromophore with an amino substituent. The fluorescence spectrum of this dye depends strongly on the amino group conformation relative to the chromophore. Thus different conformers of the chromophore can be distinguished. Here we evidence the occurrence of spectrally defined conformers and report transitions between them, revealed by single molecule spectroscopy. (C) 2000 Elsevier Science B.V. All rights reserved.