We report the spatial imaging of the photon transition probability of a single molecule at submolecular resolution. Photon imaging of a ringlike pattern is further resolved as two orthogonal vibronic transitions after incorporating spectral selectivity. A theoretical model and the calculated intensity images reveal that the transition probability is dominated by the symmetry of the positions of the tip and the transition dipole moment. This imaging technique enables the probing of the electronic and optical properties in the interior of a single molecule.

Arrays of linear, one-dimensional (1D) silver nanoparticle rows have been synthesized that demonstrate strong surface enhanced Raman scattering (SERS) that is dependent on the polarization of the incident electromagnetic radiation. Ordered arrays of 1D rows of spherical silver nanoparticles were fabricated on highly oriented pyrolytic graphite (HOPG) by physical vapor deposition (PVD) at 400 °C. Scanning electron microscopy confirmed the formation of arrays of highly parallel rows of nanoparticles. The rows are typically hundreds of microns long with particle gaps less than 10 nm and 10−1000 nm spacing between adjacent 1D rows. The polarization dependence of the SERS was characterized using thiophenol as a Raman probe molecule that was adsorbed as a monolayer on the silver nanoparticle surfaces. When incident light is polarized along the axis of the nanoparticle rows, the intensity of the Raman-scattered light was ≈20 times stronger than Raman scattered light when the incident radiation was polarized perpendicular to the axis of the nanoparticle rows. This polarization selectivity is in good agreement with our calculations that explore the electromagnetic response of the interacting nanoparticles with an incident light field.

We present a method that allows one to analyze the dipole exchange spin waves in ferromagnetic spheres, along with their interaction with spatially varying microwave magnetic fields. We present explicit calculations of the mode spectrum of such a sphere, along with the response functions which describe excitation of spin wave modes by spatially inhomogeneous fields. Our theory will prove useful for describing the dynamic response of very small ferromagnetic spheres, in the limit where exchange influences their response. Our formalism is arranged so the single sphere response function constructed here may be utilized in our recent description of the collective spin wave modes of arrays of ferromagnetic spheres.

We present calculations of the laser-induced force between metallic nanospheres, similar and dissimilar in character, and that between a metallic nanosphere and a planar surface. When the separation between these objects is in the 0.5-2 nm range, we find very strong resonances in the laser-induced force associated with excitation of plasmon resonances. Measurement of such forces will provide direct access to the plasmon enhancements of laser fields so critical to optical spectroscopy in the nanoenvironment.

We describe Raman spectroscopy measurements of distyrylbenzene (DSB) molecules equipped with plasmonic antennae in the form of silver dumbbells in aqueous solution under ambient conditions. A synthetic strategy in which the dithiolated molecule is used as the linker between silver nanospheres ensures that the molecules are attached at the intersphere gap where local fields are maximally enhanced. The measured and calculated enhancement factors are in excellent agreement. The reported method has sufficient sensitivity to also allow for the detection of molecules tethered to single spheres, with 100À1000-fold weaker enhancement. Spectral analysis allows assignment of structures and reveals that in addition to the normal Raman active modes IR active transitions appear in the Raman spectra where field gradients dominate.