Coherent XUV generation driven by sharp metal tips photoemission

It was already experimentally demonstrated that high-energy electrons can be generated using metal nanotips as active media. In addition, it has been theoretically proven that the high-energy tail of the photoemitted electrons is intrinsically linked to the recollision phenomenon. Through this recollision process it is also possible to convert the energy gained by the laser-emitted electron in the continuum in a coherent XUV photon. It means the emission of harmonic radiation appears to be feasible, although it has not been experimentally demonstrated hitherto till now. In this paper, we employ a quantum mechanical approach to model the electron dipole moment including both the laser experimental conditions and the bulk matter properties and predict is possible to generate coherent UV and XUV radiation using metal nanotips as sources. Our quantum mechanical results are fully supported by their classical counterparts.Comment: arXiv admin note: substantial text overlap with arXiv:1309.034

Oversampling in shift-invariant spaces with a rational sampling period

8 pages, no figures.It is well known that, under appropriate hypotheses, a sampling formula allows us to recover any function in a principal shift-invariant space from its samples taken with sampling period one. Whenever the generator of the shift-invariant space satisfies the Strang-Fix conditions of order r, this formula also provides an approximation scheme of order r valid for smooth functions. In this paper we obtain sampling formulas sharing the same features by using a rational sampling period less than one. With the use of this oversampling technique, there is not one but an infinite number of sampling formulas. Whenever the generator has compact support, among these formulas it is possible to find one whose associated reconstruction functions have also compact support.This work has been supported by the Grant MTM2009-08345 from the D.G.I. of the Spanish Ministerio de Ciencia y Tecnología

Probing the ZZgamma and Zgammagamma Couplings Through the Process e+e- --> nu anti-nu gamma

We study the sensitivity for testing the anomalous triple gauge couplings $ZZ\gamma$ and $Z\gamma\gamma$ via the process $e^+e^-\to \nu \bar\nu \gamma$ at high energy linear colliders. For integrated luminosities of 500 $fb^{-1}$ and center of mass energies between 0.5 and 1.5 $TeV$, we find that this process can provide tests of the triple neutral gauge boson couplings of order $10^{-4}$, one order of magnitude lower than the standard model prediction.Comment: 12 pages, 6 figure

High-order harmonic generation at high laser intensities beyond the tunnel regime

We present studies of high-order harmonic generation (HHG) at laser intensities well above saturation. We use driving laser pulses which present a particular electron dynamics in the turn-on stage. Our results predict an increasing on the harmonic yield, after an initial dropping, when the laser intensity is increased. This fact contradicts the general belief of a progressive degradation of the harmonic emission at ultrahigh intensities. We have identified a particular set of trajectories which emerges in the turn-on stage of these singular laser pulses, responsible of the unexpected growth on the harmonic efficiency at this high intensity regime. Our study combines two complementary approaches: classical analysis and full quantum mechanical calculations resulting from the numerical integration of the 3-dimensional time-dependent Schr\"odinger equation complemented with the time-frequency analysis

Determinación de los parámetros de solubilidad de Hansen para el aceite de caña de azúcar. Uso del etanol para la refinación de la cera de caña de azúcar

Currently, the refining of sugarcane wax is carried out with 95% v/v ethanol as solvent. This process has a high rate of ethanol consumption thus, the main objective of this work was to corroborate the feasibility of 95% v/v ethanol as a solvent in the refining of sugarcane wax. The suitability of its performance over other organic solvents was evaluated through the relative energy difference (RED) determined from Hansen solubility parameters (HSPs) of sugarcane oil, which were calculated using HSPiP software. HSPs turned out to be δD = 16.24 MPa½, δP = 3.21 MPa½ and δH = 10.34 MPa½, similar to those reported for pine resin and castor oil. The best solvent was 1-decanol. 95% v/v ethanol turned out to be a bad solvent. Absolute ethanol had a RED value of 0.993, which made it a better candidate since it could reduce consumption rates, and constituted an eco-friendly solvent produced in Cuba for the refining process.La refinación de la cera cruda de caña se realiza con etanol a 95% v/v, incurriendo en altos índices de consumo, por lo que el objetivo principal de este trabajo es determinar si el etanol a 95% v/v es un solvente adecuado. Su uso respecto a otros solventes orgánicos es evaluado por la diferencia de energía relativa (RED) determinada a partir de los parámetros de solubilidad de Hansen (HSPs), se calcularon usando el programa HSPiP. Los HSPs fueron δD = 16.24 MPa½, δP = 3.21 MPa½ and δH = 10.34 MPa ½, siendo similares a los reportados para la resina de pino y el aceite de ricino. El mejor solvente fue 1-decanol, el etanol del 95% v/v fue un mal solvente; el etanol absoluto con un RED= 0.993 es un mejor candidato, ya que podría reducir las tasas de consumo, manteniendo un solvente ecológico y producido en Cuba para el proceso de refinación