نتایج جستجو برای: laser ionization
تعداد نتایج: 207613 فیلتر نتایج به سال:
The development of molecular spectroscopy has enabled us to select chlorinated aromatic hydrocarbons very rapidly. In particular, the laser ionization TOFMS (time-of-flight mass spectrometry) method is expected to be useful as an on-line, selective, and sensitive method. In the present work, real-time laser ionization TOFMS measurements were carried out on gaseous chlorinated aromatic hydrocarb...
We solved one dimensional Schrodinger equation in a H2+ molecular environment by using 3 femtosecond homogeneous and nonhomogeneous laser fields. In homogeneous case, we found out that larger inter nuclear distances result in earlier ionization and also more instability in the wave packet. We deducted that the more the instability is, the more modulated the power spectrum will be. So, by choosi...
T detection and identification of molecules within complex biological matrixes (i.e., plant tissue) requires homogenization, filtration, and liquid extraction of the sample to prepare for analysis using techniques such as gas chromatography/mass spectrometry (GC/MS), liquid chromatography-mass spectrometry (LC-MS), capillary electrophoresis-mass spectrometry (CE-MS), and LC-NMR. Direct analysis...
We theoretically investigate the electronic dynamics in the hydrogen molecular ion at fixed intermediate internuclear distances in two-dimensional space for the electron in a linearly polarized laser field. Our results of numerical simulations confirm the predictions of multiple bursts of ionization within a half cycle of the laser field oscillation as recently reported for one-dimensional mode...
Photofrin (porfimer sodium) is a porphyrin derivative used in the treatment of a variety of cancers by photodynamic therapy. This oligomer complex and a variety of porphyrin monomers, dimers and trimers were analyzed with five different mass spectral ionization techniques: fast atom bombardment, UV and IR matrix-assisted laser desorption/ionization, electrospray ionization, and laser desorption...
Few-photon multiple ionization of Ne and Ar atoms by strong vacuum ultraviolet laser pulses from the free-electron laser at Hamburg was investigated differentially with the Heidelberg reaction microscope. The light-intensity dependence of Ne2+ production reveals the dominance of nonsequential two-photon double ionization at intensities of I<6x10(12) W/cm2 and significant contributions of three-...
We investigate molecular dynamics of multiple ionization in N2 through multiple core-level photoabsorption and subsequent Auger decay processes induced by intense, short x-ray free electron laser pulses. The timing dynamics of the photoabsorption and dissociation processes is mapped onto the kinetic energy of the fragments. Measurements of the latter allow us to map out the average internuclear...
ABSTRACT The performance of porous silicon and cobalt glancing angle deposited (GLAD) thin films for matrix-free laser desorption/ionization-MS analysis of carbohydrates, peptides and drugs with molecular weights < 2,500 Dalton is presented. The performance of these films for selected peptides and small drugs detection is similar to the best reported for desorption/ionization on electrochemical...
We have studied the ionization of Rydberg–excited xenon atoms in THz-laser fields and by quantum dynamical calculations. The experimental threshold laser field strength for 10% ionization probability follows an n (ω/2π =1.04 THz) dependence (n effective principal quantum number) with additional weak resonance structures and shows that ionization does not occur by a Landau–Zener mechanism. At sc...
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