Resonantly suppressed transmission and anomalously enhanced light absorption in ultrathin metal films

We study light diffraction in the periodically modulated ultrathin metal films both analytically and numerically. Without modulation these films are almost transparent. The periodicity results in the anomalous effects, such as suppression of the transmittance accompanied by a strong enhancement of the absorptivity and specular reflectivity, due to excitation of the surface plasmon polaritons. These phenomena are opposite to the widely known enhanced transparency of periodically modulated optically thick metal films. Our theoretical analysis can be a starting point for the experimental investigation of these intriguing phenomena.Comment: 4 pages, 5 figure

Warm turbulence in the Boltzmann equation

We study the single-particle distributions of three-dimensional hard sphere gas described by the Boltzmann equation. We focus on the steady homogeneous isotropic solutions in thermodynamically open conditions, i.e. in the presence of forcing and dissipation. We observe nonequilibrium steady state solution characterized by a warm turbulence, that is an energy and particle cascade superimposed on the Maxwell-Boltzmann distribution. We use a dimensional analysis approach to relate the thermodynamic quantities of the steady state with the characteristics of the forcing and dissipation terms. In particular, we present an analytical prediction for the temperature of the system which we show to be dependent only on the forcing and dissipative scales. Numerical simulations of the Boltzmann equation support our analytical predictions.Comment: 4 pages, 5 figure

New mechanism for non-trivial intra-molecular vibrational dynamics

We investigate the time evolution process of one selected (initially prepared by optical pumping) vibrational molecular state, coupled to all other intra-molecular vibrational states of the same molecule, and also to its environment. Molecular states forming the first reservoir are characterised by a discrete dense spectrum, whereas the environment reservoir states form a continuous spectrum. Assuming the equidistant reservoir states we find the exact analytical solution of the quantum dynamic equations. System reservoirs couplings yield to spontaneous decay of the states, whereas system-reservoir exchange leads to recurrence cycles and Loschmidt echo and double resonances at the interlevel reservoir transitions. Due to these couplings the system $S$ time evolution is not reduced to a simple exponential relaxation. We predict various regimes of the system dynamics, ranging from exponential decay to irregular damped oscillations. Namely, we show that there are four possible dynamic regimes of the evolution: (i) - independent of the environment exponential decay suppressing backward transitions, (ii) Loschmidt echo regime, (iii) - incoherent dynamics with multicomponent Loschmidt echo, when the system state exchanges its energy with many states of the reservoir, (iv) - cycle mixing regime, when the long term system dynamics appear to be random. We suggest applications of our results for interpretation of femtosecond vibration spectra of large molecules and nano-systems.Comment: 11 pages, 2 figure

Investigation of the spectra of coupled polaritons on the periodically modulated metallic layer and the narrow regions of anomalous transparency

The paper deals with the theoretical investigation of plane, normally incident electromagnetic wave transmission through the flat metal film whose dielectric constant has small periodical sinusoidal modulation in one dimension parallel to the projection of the electric field onto the film surface. The dependencies of the film transmittancy on the parameters of the problem (frequency, modulation depth and absorption) are examined. It is shown that the film transmittancy increases considerably when the conditions for resonance interaction of an incident electromagnetic wave with surface plasmon polaritons (SPPs) are met. It is found that for small but finite absorption there are two frequencies in the vicinity of which the transmittancy can achieve the values of the order of unity due to resonances on symmetric and antisymmetric (relative to the mean plane) SPP modes. It is shown that for each value of absorption there exists a certain optimal modulation depth, which maximizes the resonance transparency.Comment: 18 pages, 8 figures, proceeding of conference "Plasmonics: metallic nanostructures and their optical properties", SPIE's 48-th Annual Meeting, 3-8 August, 2003, San Diego, US