نتایج جستجو برای: laser ionization
تعداد نتایج: 207613 فیلتر نتایج به سال:
This work presents a novel method for direct desorption/ ionization of analytes from sol-gel-derived film. 2,5-Dihydroxy benzoic acid (DHB), a common MALDI matrix, was incorporated into a sol-gel polymeric structure. The sol-gel-derived DHB thin film can assist the mass analysis of analytes by laser desorption/ionization, with a matrix interference-free background in the mass spectra. The sol-g...
We predict photoelectron angular distributions for double ionization of Li- by both weak and intense ultrashort, linearly polarized laser pulses by direct numerical integration of the three-dimensional, time-dependent Schrödinger equation. Li- is treated as a two-active electron system. Near threshold, for low intensity we recover general features of angular distributions for one-photon double ...
Measurements of the odd-even effect in the mass spectrometric analysis ofTi and Os isotopes by resonance ionization mass spectrometry have been performed forM = + 1, 0 and -1 transitions. Under saturating conditions of the ionization and forM = + 1 transitions odd-even effects are reduced below the 0.5% level. Depending on the polarization state of the laser large odd isotope enrichments are ob...
The plateau features that characterize the low-frequency spectra of fundamental strong-fi eld processes such as harmonic generation, above-threshold ionization and laserassisted electron-atom scattering are shown to exist also for photon energies Eγ of the order of the energy |E0| of a bound electron. The existence of these rescattering effects in such a high-frequency (and thus nontunnelling) ...
Ablation plumes caused by short-pulse laser irradiation provide conditions which are well suited to the formation of nanoclusters. The high saturation ratios and presence of ionization lead to extraordinarily high nucleation rates and small critical radii. We have explored the homogeneous nucleation and heterogeneous growth of condensate from Si targets expanding into a low-pressure He ambient ...
Midinfrared strong-field laser ionization offers the promise of measuring holograms of atoms and molecules, which contain both spatial and temporal information of the ion and the photoelectron with subfemtosecond temporal and angstrom spatial resolution. We report on the scaling of photoelectron holographic interference patterns with the laser pulse duration, wavelength, and intensity. High-res...
The authors time resolve molecular motion in bound state, ionic potentials that leads to bond cleavage during the interaction with intense, ultrafast laser fields. Resonances in molecular ions play an important role in dissociative ionization with ultrafast laser fields, and the authors demonstrate how these resonances evolve in time to produce dissociation after initial strong-field ionization...
Using a simple model of strong-field ionization of atoms that generalizes the well-known 3-step model from 1D to 3D, we show that the experimental photoelectron angular distributions resulting from laser ionization of xenon and argon display prominent structures that correspond to electrons that pass by their parent ion more than once before strongly scattering. The shape of these structures ca...
In laser desorption of a series of cyclically 9-substituted adenines, followed by multiphoton ionization, we observed characteristic fragmentation. This is in marked contrast to laser desorption under identical conditions of cyclically 9-substituted guanines, for which we obtained predominantly the parent mass. By applying resonant 2 photon ionization spectroscopy (R2PI) to the laser-desorbed, ...
From the pulse length dependence of the absorption of intense ultrashort laser pulses focused inside fused silica, we reveal the role field-assisted collisional ionization plays in the multiphoton ionization process. This constitutes a cold avalanche ionization mechanism that persists at pulse lengths considered too short for a traditional avalanche.
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