ABSTRACT
A combination of advanced synthetic and single molecule spectroscopic techniques allowed us to demonstrate that macrocycles, covalently bound to a conjugated polymer backbone, raise the effective chain persistence length by at least a factor of 5.
ABSTRACT
We investigate the correlation between plasmon-enhanced nonlinear white-light emission and single-molecule surface-enhanced Raman scattering (SERS) on fractal silver films using a conjugated polymer as a versatile analyte. Single molecule resonance SERS is preferentially observed from sample positions which do not exhibit nonlinear light emission under infrared excitation. The results suggest that the broad emission background often associated with single molecule SERS may not be intrinsic to the huge optical field amplifications characteristic of SERS. The two-photon imaging technique promises to offer a facile approach to prescreen substrates for their single molecule SERS capability.
ABSTRACT
Simultaneous surface enhanced Raman scattering (SERS) and fluorescence is demonstrated from single conjugated polymer chains. As resonance enhancement of SERS depends on the spectral overlap of the polymer's absorption and the incident laser, resonance Raman and fluorescence effectively probe the absorbing and emitting part of the polymer, respectively. The optical phonon energies change along the polymer chain, providing a window to spatially track excited state relaxation. Whereas a mean spatial redistribution of the excitation is witnessed by a change in vibronic fingerprint following interchromophoric energy transfer, intrachromophoric exciton self-trapping leaves the vibrations unchanged.
