نتایج جستجو برای: laser ionization
تعداد نتایج: 207613 فیلتر نتایج به سال:
Abstract. When considering intense particle or laser beams propagating in dense plasma or gas, ionization plays an important role. Impact ionization and tunnel ionization may create new plasma electrons, altering the physics of wakefield accelerators, causing blue shifts in laser spectra, creating and modifying instabilities, etc. Here we describe the addition of an impact ionization package in...
OF THESIS DESK-TOP SIZE HIGH REPETITION RATE 46.9 NM CAPILLARY DISCHARGE LASER AS PHOTOIONIZATION SOURCE FOR PHOTOCHEMISTRY APPLICATIONS A portable high repetition rate desktop-size capillary discharge laser emitting at a wavelength of 46.9 nm (26.5 eV photon energy) was demonstrated and used as a photoionization source in nanocluster mass spectroscopy. The high photon energy allows the single-...
Silicon nanopowder (5-50 nm) was applied as a matrix for the analysis of small molecules in laser desorption/ionization mass spectrometry. In contrast with conventional matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry, the matrix background interference in the low mass range was significantly reduced. Effects of the particle size and sample preparation proced...
Laser desorption/ionization from a single-crystal silicon surface was performed using a laser operating in the 3-microm region of the mid-infrared. Analyte molecules up to 6 kDa were ionized with no added matrix. As with ultraviolet desorption/ionization from porous silicon (DIOS), IR laser desorption from silicon does not produce matrix ions that can interfere with analysis of low-mass analyte...
Recently an increasing interest in the investigation of relativistic ionization phenomena has been observed [1–10]. Relativistic effects will appear if the electron velocity in the initial bound state or in the final state is comparable with the speed of light. The initial state should be considered relativistic in the case of inner shells of heavy atoms [3,4]. In a recent paper [10] the photoi...
Single pulse transmissivity and reflectivity of fused silica irradiated by tightly focused 90 fs laser pulses at a center wavelength of 800 nm are numerically and experimentally investigated to study the role of nonlinear photoionization and avalanche ionization processes in free electron generation. The laser beam inside fused silica is modeled with a 2+1 -dimensional propagation equation whic...
Trace explosives residues of CL20 (hexanitrohexazaisowurtzitane) and RDX (hexahydro-1,3,5-hexanitro-1,3,5-triazine are measured in real-time by surface laser photofragmentation-fragment detection (SPFFD) spectroscopy at ambient conditions. A 248nm laser photofragments the target residue on a substrate, and a 226-nm laser ionizes the resulting NO fragment by resonance-enhanced multiphoton ioniza...
Theoretical study on H2(+) in an intense infrared laser field on the attosecond time scale reveals that the molecular ion shows multiple bursts of ionization within a half-cycle of the laser field oscillation, in contrast to the widely accepted tunnel ionization picture for an atom. These bursts are found to be induced by transient localization of the electron at one of the nuclei, and a relati...
A comprehensive model of ultrafast laser-induced plasma generation intended for coupling with pulse propagation simulations in transparent solids is introduced. It simultaneously accounts for the changing spectrum of a propagating ultrashort laser pulse while coupling to the evolution of the energy-resolved nonequilibrium free-carrier distribution. The presented results indicate that strong pul...
In this paper we report on inner ionization of Xen clusters (n = 55−2171) in ultraintense Gaussian laser fields (peak intensity I = 1015−1020 Wcm−2, pulse width τ = 25 fs, frequency 0.35 fs−1). The cluster inner ionization process is induced by the barrier suppression ionization (BSI) mechanism and by electron impact ionization (EII), which occurs sequentially with the BSI. We address electron ...
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