Zeolite-dye micro lasers

We present a new class of micro lasers based on nanoporous molecular sieve host-guest systems. Organic dye guest molecules of 1-Ethyl-4-(4-(p-Dimethylaminophenyl)-1,3-butadienyl)-pyridinium Perchlorat were inserted into the 0.73-nm-wide channel pores of a zeolite AlPO$_4$-5 host. The zeolitic micro crystal compounds where hydrothermally synthesized according to a particular host-guest chemical process. The dye molecules are found not only to be aligned along the host channel axis, but to be oriented as well. Single mode laser emission at 687 nm was obtained from a whispering gallery mode oscillating in a 8-$\mu$m-diameter monolithic micro resonator, in which the field is confined by total internal reflection at the natural hexagonal boundaries inside the zeolitic microcrystals.Comment: Accepted for publication in Phys. Rev. Let

Spectral properties of quantized barrier billiards

The properties of energy levels in a family of classically pseudointegrable systems, the barrier billiards, are investigated. An extensive numerical study of nearest-neighbor spacing distributions, next-to-nearest spacing distributions, number variances, spectral form factors, and the level dynamics is carried out. For a special member of the billiard family, the form factor is calculated analytically for small arguments in the diagonal approximation. All results together are consistent with the so-called semi-Poisson statistics.Comment: 8 pages, 9 figure

Electronic structure of small fullerenes : evidence for the high stability of C32

The electronic structure of small fullerenes determined experimentally by anion photoelectron spectroscopy is compared with calculations. A huge mass signal and a large gap of 1.3 eV comparable to the gap of C70 have been found for C32, indicating that this cluster is the most stable fullerene below C60. Also C36, C44, and C50 exhibit large gaps and surprisingly high stabilities. The criteria for the selection of clusters sufficiently stable to form a cluster material are discussed

Alignment of a Laser Dye in the Channels of the AlPO₄-5 Molecular Sieve

Solid-state laser systems based on molecular sieves may not be far away. Here, the incorporation and linear alignment of a pyridine-based laser dye in the channels of AlPO4-5 is reported and the spectroscopic properties of the composite are investigated. A first indication that AlPO4-5–laser dye composite crystals show laser action is demonstrated for microcrystals with a highly intergrown shap

Ordered porous materials as media for the organization of matter on the nanoscale

Ordered porous inorganic compounds can now be synthesized with pore sizes between 0.3 nm and several tens of nanometers. The sharp pore size distribution of such materials and the ordered pore arrangement open possibilities for using them to organize matter on the nanometer scale. This overview highlights different aspects of this topic, using four selected examples: the spatial organization of molecules with high molecular hyperpolarizability to create a frequency-doubling element; the encapsulation of a laser dye which results in a new class of solid-state lasers; the encapsulation of small metal clusters in mesoporous ordered oxides; and the encapsulation of semiconductor clusters in such oxides