A simple bulk model of electron-phonon coupling in metals has been surprisingly successful in explaining experiments on metal films that actually involve surface-or other low-dimensional phonons. However, by an exact application of this standard model to a semi-infinite substrate with a free surface, making use of the actual vibrational modes of the substrate, we show that such agreement is fortuitous, and that the model actually predicts a low-temperature crossover from the familiar T 5 temperature dependence to a stronger T 6 log T scaling. Comparison with existing experiments suggests a widespread breakdown of the standard model of electron-phonon thermalization in metals.PACS numbers: 63.22.+m, 85.85.+j The coupling between electrons and phonons plays a crucial role in determining the thermal properties of nanostructures. The widely used "standard" model of low temperature electron-phonon thermal coupling and hot-electron effects in bulk metals [1, 2] assumes (i) a clean three-dimensional free-electron gas with a spherical Fermi surface, rapidly equilibrated to a temperature T el ; (ii) a continuum description of the acoustic phonons, which have a temperature T ph ; (iii) a negligible Kapitzalike thermal boundary resistance [3] between the metal and any surrounding dielectric, an assumption that is often well justified experimentally; and (iv), a deformationpotential electron-phonon coupling, expected to be the dominant interaction at long-wavelengths. In a bulk metal, the net rate P of thermal energy transfer between the electron and phonon subsystems is where V el is the volume of the metal, and

A fluorescence behavior controllable conjugated polymer (CP)-based fluorescent film was developed by chemical attaching poly(2,5-dihexadecyloxyphenyleneethynylene) (M-PPEs) onto a glass plate surface. It was revealed that the profile of the fluorescence emission spectrum of the film depended upon the polarity of its medium. This dependence has been attributed to the alteration of the conformation of the side chains of the polymer in immobilized state. In “poor” solvents or vapors, the side chains may adopt a compact coil conformation, resulting in aggregation of the immobilized polymers, and thereby fluorescence emission of the film is reduced because of the so-called aggregation-induced fluorescence quenching effect. Whereas in “good” solvents or vapors, the side chains tend to be swollen and adopt extended or loose coil structure, thereby preventing aggregation of the polymers, coupled with increasing of the fluorescence emission. Interestingly, this alteration process is fully reversible, and the retention time for each equilibration is less than 1 min. The film is also responsible for the changes in the compositions of mixture solvents, such as THF/methanol. In particular, two-input INH and OR logic gates were presented on the basis of the film. No doubt, this finding can be taken as a new strategy for the design of CPs and self-assembled monolayer (SAM)-based fluorescent sensing films and will definitely expand their applications.

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Multi-dimensional metallic nanostructures were fabricated by self-assembling silver nanoparticles on 3-aminopropyltrimethoxysilane-modified glass substrate and using p-aminothiophenol molecule as a linker. Surface enhanced fluorescence was investigated for Rhodamine 6G fluorophore molecules on the prepared 2D and 3D substrates. The experimental observation showed that the 3D nanostructured substrate presented stronger fluorescence enhancement, comparing with what was observed on the 2D nanoparticle arrays. Higher intensity of local electric field and stronger coupling of surface plasmon resonance in 3D silver nanostructure enhanced the excitation and emission of fluorophore molecules more effectively, leading to a stronger fluorescence enhancement on 3D nanostructured substrate. The result suggests that a metallic substrate with 3D nanostructures can produce better fluorescence enhancement, which is important for studying the mechanism and expanding the potential applications of enhanced fluorescence effect.

We have observed a ''multiple devil's staircase'' in a one-dimensional ͑1D͒ map including two discontinuous regions. Both end points of each phase-locked plateau in the staircase are confined by the conditions of collision between the periodic orbit and one of the discontinuous region edges. There are more modes of the collision than in a 1D map including only one discontinuous region. This complexity makes the whole staircase lose monotonicity, self-similarity, and the ''Farey tree rule'' for a description of the plateau length distribution. However, the staircase consists of many conventional complete devil's staircases, many of them having their own threshold of transfer to chaos via a type-V intermittency. Therefore the parameter space can be divided into three parts. In the first part only periodic attractors appear. In the second part periodic and chaotic attractors appear alternatively, and the system displays type-V intermittency frequently. In the last part only chaotic attractors exist.