A first order Tsallis theory

We investigate first-order approximations to both i) Tsallis' entropy $S_q$ and ii) the $S_q$-MaxEnt solution (called q-exponential functions $e_q$). It is shown that the functions arising from the procedure ii) are the MaxEnt solutions to the entropy emerging from i). The present treatment is free of the poles that, for classic quadratic Hamiltonians, appear in Tsallis' approach, as demonstrated in [Europhysics Letters {\bf 104}, (2013), 60003]. Additionally, we show that our treatment is compatible with extant date on the ozone layer.Comment: 4 figures adde

Exciton-phonon scattering and photo-excitation dynamics in J-aggregate microcavities

We have developed a model accounting for the photo-excitation dynamics and the photoluminescence of strongly coupled J-aggregate microcavities. Our model is based on a description of the J-aggregate film as a disordered Frenkel exciton system in which relaxation occurs due to the presence of a thermal bath of molecular vibrations. In a strongly coupled microcavity exciton-polaritons are formed, mixing superradiant excitons and cavity photons. The calculation of the microcavity steady-state photoluminescence, following a CW non resonant pumping, is carried out. The experimental photoluminescence intensity ratio between upper and lower polariton branches is accurately reproduced. In particular both thermal activation of the photoluminescence intensity ratio and its Rabi splitting dependence are a consequence of the bottleneck in the relaxation, occurring at the bottom of the excitonic reservoir. The effects due to radiative channels of decay of excitons and to the presence of a paritticular set of discrete optical molecular vibrations active in relaxation processes are investigared.Comment: 8 pages, 6 figure

Proposal for soft-x-ray and XUV lasers in capillary discharges

Includes bibliographical references (page 567).Capillary plasmas with large length-to-diameter ratios (1/d > 100) are proposed as amplification media for soft-x-ray and XUV radiation by direct discharge excitation. The capillary geometry provides a small volume and an adequate resistance for ohmic heating. Heat conduction to the capillary walls provides rapid cooling of the plasma during the decay of the excitation pulse, resulting in a large recombination rate and a population inversion. A time-dependent collisional-radiative model of the capillary plasma predicts gains of the order of 5 cm-1 in the 18.2-nm line of C VI