Weak satellites in S-1<--S-0 excitation spectra of natural-abundance pentacene in p-terphenyl due to position-specific C-13 isotope shifts were observed. An assignment of these satellites to the... Show moreWeak satellites in S-1<--S-0 excitation spectra of natural-abundance pentacene in p-terphenyl due to position-specific C-13 isotope shifts were observed. An assignment of these satellites to the various carbon positions is derived. The extremely narrow inhomogeneous linewidth allowed selective excitation of pentacene molecules with C-13 in specific positions. Spectra of the magnetic-resonance transition between triplet sublevels of such ensembles, and of individual pentacene molecules showed position-specific C-13 hyperfine broadening. (C) 1996 American Institute of Physics. Show less
Köhler, J.; Brouwer, A.C.J.; Groenen, E.J.J.; Schmidt, J. 1996
Applying methods developed for single molecule spectroscopy to small ensembles, we have recorded high-resolution fluorescence-excitation spectra for pentacene in all substitutional sites of a p... Show moreApplying methods developed for single molecule spectroscopy to small ensembles, we have recorded high-resolution fluorescence-excitation spectra for pentacene in all substitutional sites of a p-terphenyl single crystal. The difference in intersystem crossing efficiency for pentacene molecules in the various substitutional sites is discussed on the basis of these spectra and data from optically detected magnetic resonance experiments. Show less
Meer, H. van der; Disselhorst, J.A.J.M.; Köhler, J.; Brouwer, A.C.J.; Groenen, E.J.J.; Schmidt, J. 1995
We describe an insert for optical and magnetic-resonance experiments on single molecules in a solid matrix at liquid-helium temperatures. The experimental arrangement allows in situ adjustment of... Show moreWe describe an insert for optical and magnetic-resonance experiments on single molecules in a solid matrix at liquid-helium temperatures. The experimental arrangement allows in situ adjustment of the focusing lens and of the sample. A parabolic mirror serves to collect the fluorescence emission and to direct the light onto a photodetector. Microwaves can be irradiated through a coil around the sample while a superconducting magnet provides the possibility of a stationary magnetic field. (C) 1995 American Institute of Physics. Show less
Köhler, J.; Brouwer, A.C.J.; Groenen, E.J.J.; Schmidt, J. 1995
Individual pentacene-d(14) molecules doped into a p-terphenyl-d(14) host crystal have been studied by optically detected electron paramagnetic resonance spectroscopy. The magnetic resonance... Show moreIndividual pentacene-d(14) molecules doped into a p-terphenyl-d(14) host crystal have been studied by optically detected electron paramagnetic resonance spectroscopy. The magnetic resonance transitions between the triplet sublevels of the pentacene molecule and the splitting of the resonance lines for a molecule that contains a carbon-13 nucleus have been observed in an edernal magnetic field. This splitting is caused by the hyperfine interaction of the triplet electron spin with the single carbon-13 nuclear spin. Show less
Köhler, J.; Brouwer, A.C.J.; Groenen, E.J.J.; Schmidt, J. 1994
We report the observation of the broadening of a magnetic-resonance transition between triplet sublevels of a single pentacene molecule owing to the interaction of the triplet electron spin with a... Show moreWe report the observation of the broadening of a magnetic-resonance transition between triplet sublevels of a single pentacene molecule owing to the interaction of the triplet electron spin with a single C-13 nuclear spin. Analysis of this broadening allows the assignment of particular features in the fluorescence-excitation spectrum to pentacene molecules containing C-13 isotopes in specific positions. Show less
