Self‐consistent interaction potential for a molecule adsorbed on a dielectric surface: A symmetric top molecule on an ionic crystal

Electrodynamic interaction between a nanoparticle and the surface of a solid

We study the interaction between a nanoparticle and the surface of a solid in the framework of the local-field method. Assuming that the nanoparticle is characterized by a finite nonlinear polarizability, we obtain the interaction potential that is repulsive at short range and has an attractive long-range tail. Our numerical analysis shows that this potential strongly depends on the shape and size of the particle. Further, we study the particle-surface interaction in the presence of a surface plasmon polariton propagating along the interface. It is shown that the excitation of the surface wave leads to a drastic (about one order of magnitude) increase in the binding energy. Potential applications of this effect are discussed.

Plasmon resonances and near-field optical microscopy: a self-consistent theoretical model

Electromagnetic optical interactions between a small metal sphere and a metallic surface are studied by using a self-consistent approach in the presence of an external field. The intensity scattered by the metal particle is given for different polarizations of the incident field. This quantity, determined from a local treatment of the response function of the two interacting systems, exhibits a spatial dependence with respect to the approach distance close to that obtained from recent experimental studies. Moreover, at large separation, retardation effects included from a dipolar propagator give rise to pseudoperiodic oscillations such as the ones observed in reflection near-field optical microscopy. In the near-field range, plasmon modes of the whole system probe surface introduce narrow resonances in the scattered intensity versus the probe-sample separation.

Model for reflection near field optical microscopy

We discuss a model that describes the optical interactions between a dielectric tip and a surface exhibiting roughness of subwavelength size (infinite tracks). Such a model gives new insight into the resolution achievable by scanning near field optical microscopy. The dielectric tip is schematized as a cone whose extremity reduces to a small sphere acting as a dipolar scattering center, allowing separation of the contributions from the near field lying at the air-sample interface of other long range terms associated with the progressive waves coming from the surface. It is shown that because of its fast spatial dependence, the near field detected by the tip contains subwavelength features of the object. Relationships with preliminary experiments are discussed.