Visible and ultraviolet photoelectron spectroscopy of fullerenes using femtosecond laser pulses

Photoelectron spectra are presented for C60 excited with fs pulses of wavelengths 532 and 267 nm. The spectra indicate a quick redistribution of the excitation energy. Excitation of SAMO states is observed with 532 nm excitation, but due to the relatively large photon energy of the 267 nm pulses, these orbitals are not populated for this wavelength

Catalysis of impurities coalescence by quantized vortices in superfluid helium with nanofilaments formation

The dramatic effect of quantized vortices in superfluid helium on the rate of coalescence of suspended impurities has been predicted; such catalytic process should result in formation of fiber-like structures having primarily nanothickness. That should be valid for any impurity and it may be used as a base for the universal method of nanowires and nanotubes producing. The experiments on molecular hydrogen imbedding into liquid helium supported these conclusions. They showed that: (i) in normal liquid He the coalescence led to formatting spherical microparticles carried by turbulent motion of a liquid; (ii) in the superfluid only very long filaments were observed, they behaved as quantized vortices should do. These filaments are fiber-like hydrogen crystals and they survived liquid helium transition to normal state. The promises for using this phenomenon in basic and applied sciences have been outlined

Low-temperature electrical discharge through solid xenon

The uniform self-sustained electrical discharge through solid xenon has been realized and studied. The multiplication of electrons proceeds in the noble gas above the xenon crystal interface whereas a positive feedback is realized at the account of multiple exciton formation by excess electrons drifted through the crystal: molecular excitons emit VUV photons which knocked out secondary electrons from photosensitive cathode. The discharge was stimulated by short electrical spark along the sample axes. The discharge electrical properties as well as the spectra of solid xenon electroluminescence in UV and visible have been studied. Electric discharge in solid xenon was proved to be an effective source of UV radiation and a convenient tool to study the processes involving excitons and electrons in solid xenon at high pressures

Superposition of photon- and phonon- assisted tunneling in coupled quantum dots

We report on electron transport through an artificial molecule formed by two tunnel coupled quantum dots, which are laterally confined in a two-dimensional electron system of an Al$_x$Ga$_{1-x}$As/GaAs heterostructure. Coherent molecular states in the coupled dots are probed by photon-assisted tunneling (PAT). Above 10 GHz, we observe clear PAT as a result of the resonance between the microwave photons and the molecular states. Below 8 GHz, a pronounced superposition of phonon- and photon-assisted tunneling is observed. Coherent superposition of molecular states persists under excitation of acoustic phonons.Comment: 5 pages, 4 figure

Exile Vol. II No. 2

SHORT STORIES The Jagged Edge by Marge Sessions 16-22 Friday Is a Lucky Day by Nil Muldur 28-33 Punk Days by Jim Gallant 37-41 ESSAYS A Re-examination of Faith by Barbara Haupt 23-27 A World Manifesto by Gordon Harper 34-36 SKETCH Tom Gordon: A Portrait by David L. Crook 6-15 POETRY Striving After Wind by Jesse Matlack 15 Quiet by E. B. Chaney 22 Faith or Flight by Marylyn Hull 36 Bernadette by Sally Falch 42-44 In this issue the editors of EXILE are proud to publish A Re-examination of Faith by Barbara Haupt. This story has been awarded the second Denison Book Store - EXILE Creative Writing Prize

Fano Resonances in Electronic Transport through a Single Electron Transistor

We have observed asymmetric Fano resonances in the conductance of a single electron transistor resulting from interference between a resonant and a nonresonant path through the system. The resonant component shows all the features typical of quantum dots, but the origin of the non-resonant path is unclear. A unique feature of this experimental system, compared to others that show Fano line shapes, is that changing the voltages on various gates allows one to alter the interference between the two paths.Comment: 8 pages, 6 figures. Submitted to PR

A Solvable Regime of Disorder and Interactions in Ballistic Nanostructures, Part I: Consequences for Coulomb Blockade

We provide a framework for analyzing the problem of interacting electrons in a ballistic quantum dot with chaotic boundary conditions within an energy $E_T$ (the Thouless energy) of the Fermi energy. Within this window we show that the interactions can be characterized by Landau Fermi liquid parameters. When $g$, the dimensionless conductance of the dot, is large, we find that the disordered interacting problem can be solved in a saddle-point approximation which becomes exact as $g\to\infty$ (as in a large-N theory). The infinite $g$ theory shows a transition to a strong-coupling phase characterized by the same order parameter as in the Pomeranchuk transition in clean systems (a spontaneous interaction-induced Fermi surface distortion), but smeared and pinned by disorder. At finite $g$, the two phases and critical point evolve into three regimes in the $u_m-1/g$ plane -- weak- and strong-coupling regimes separated by crossover lines from a quantum-critical regime controlled by the quantum critical point. In the strong-coupling and quantum-critical regions, the quasiparticle acquires a width of the same order as the level spacing $\Delta$ within a few $\Delta$'s of the Fermi energy due to coupling to collective excitations. In the strong coupling regime if $m$ is odd, the dot will (if isolated) cross over from the orthogonal to unitary ensemble for an exponentially small external flux, or will (if strongly coupled to leads) break time-reversal symmetry spontaneously.Comment: 33 pages, 14 figures. Very minor changes. We have clarified that we are treating charge-channel instabilities in spinful systems, leaving spin-channel instabilities for future work. No substantive results are change

Bose-Einstein condensates in a one-dimensional double square well: Analytical solutions of the Nonlinear Schr\"odinger equation and tunneling splittings

We present a representative set of analytic stationary state solutions of the Nonlinear Schr\"odinger equation for a symmetric double square well potential for both attractive and repulsive nonlinearity. In addition to the usual symmetry preserving even and odd states, nonlinearity introduces quite exotic symmetry breaking solutions - among them are trains of solitons with different number and sizes of density lumps in the two wells. We use the symmetry breaking localized solutions to form macroscopic quantum superpositions states and explore a simple model for the exponentially small tunneling splitting.Comment: 11 pages, 11 figures, revised version, typos and references correcte

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results