Ionita, P., Caragheorgheopol, A., Gilbert, B.C. and Chechik, V. (2005) Dipole-dipole interactions in spin-labeled Au nanoparticles as a measure of interspin distances. Journal of Physical Chemistry B, 109 (9). pp. 3734-3742. ISSN 1520-6106
A series of Au nanoparticles modified with a nitroxide-functionalized ligand was prepared with a range of spin-label coverage. The X-band EPR spectra of frozen solutions of these nanoparticles showed coverage-dependent line-broadening due to dipole−dipole interactions between spin labels. We developed a methodology to analyze such spectra in terms of geometrical features of the nanoparticles (e.g., Au core size and the length of the spin-labeled ligand). Our method is based on the assumption that the spectral line shape is determined by the average distance between nearest-neighboring spin labels adsorbed on the Au particle. Geometrical and statistical analysis then relates this distance to the line shape parameter d1/d, which was calibrated using a model system. Application of this methodology to the experimental spectra provided information about the conformation of ligands on the Au surface. We found that, if the spin-labeled ligand is substantially longer than the surrounding protecting layer, it does not adopt a fully stretched conformation but wraps around the particle immediately above the layer of surrounding ligand. Our results also show that the ligands do not adsorb cooperatively on the Au surface.
|Institution:||The University of York|
|Academic Units:||The University of York > Chemistry (York)|
|Depositing User:||York RAE Import|
|Date Deposited:||20 Apr 2009 11:45|
|Last Modified:||20 Apr 2009 11:45|
|Publisher:||American Chemical Society|