Biomedical subjects
Publications and source records attributed to M A Noginov.
We have observed the compensation of loss in a metal by a gain in a dielectric medium in the mixture of an Ag aggregate and a Rhodamine 6G dye. The demonstrated sixfold enhancement of the Rayleigh scattering is the evidence of the enhancement of the surface-plasmon resonance. The reported experimental observation facilitates many applications of nanoplasmonics.
Equilibrium atomic geometries of rhodamine 6G (R6G) dye molecule dimers are studied using density-functional theory. Electron-energy structure and optical properties of R6G H and J dimers are calculated using the generalized gradient approximation method with ab initio pseudopotentials. Our theory predicts substantial redshifts or blueshifts of the optical absorption spectra of R6G dye molecules after aggregation in J or H dimers, respectively. Predicted optical properties of R6G dimers are interpreted in terms of interatomic and intermolecular interactions. Results of the calculations are discussed in comparison with experimental data.
Comparing the absorption spectrum of a single-crystalline material and the reflection spectrum of its powder, we have derived a simple empirical formula for the reflection coefficient of absorbing powder. The proposed equation, which slightly resembles the Lambert-Beer law for transmission, does not correspond to the equation derived in the approximation of a simple one-dimensional diffusion model.