نتایج جستجو برای: electron lifetime
تعداد نتایج: 359790 فیلتر نتایج به سال:
Andersson, M. 2000. Tuning Electron Transfer Reactions by Selective Excitation in Porphyrin Acceptor Assemblies. Acta Universitatis Upsaliensis. Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 578. 58 pp. Uppsala. ISBN 91-554-48437. This thesis concerns electron transfer reactions from different excited states in porphyrins, and the effect of changing...
The hyperfine structure of highly charged 238 92 U ions with rotationally excited nuclei Abstract The hyperfine structure (hfs) of electron levels of 238 92 U ions with the nucleus excited in the low-lying rotational 2 + state with an energy E 2 + = 44.91 keV is investigated. In hydrogenlike uranium, the hfs splitting for the 1s 1/2-ground state of the electron constitutes 1.8 eV. The hyperfine...
The structure and defects of nanodiamonds influence the hydrogen sorption capacity. Positronium can be used as a sensor for detecting places with the most efficient capture of hydrogen atoms. Hydrogenation of carbon materials was performed from gas atmosphere. The concentration of hydrogen absorbed by the sample depends on the temperature and pressure. The concentration 1.2 wt % is achieved at ...
The cross section for bond breaking at the site of a dissociative temporary negative ion state through the dissociative electron attachment process can be considerably enhanced by the presence of a second longer-lived temporary negative ion state elsewhere in the molecule, even one quite remote from the first. In a series of chloroalkenes possessing both C-Cl and C==C bonds separated by various...
Using reflectivity and picosecond time-resolved photoluminescence, we have studied the intrinsic optical properties of negatively charged excitons in modulation doped CdTe quantum wells. In emission, we observe simultaneously a low energy exponential tail in the charged exciton spectral line and a linear increase of its radiative lifetime with temperature. In absorption, we find a consistent de...
We report the observation of lifetime-enhanced transport (LET) based on perpendicular valleys in silicon by transport spectroscopy measurements of a two-electron system in a silicon transistor. The LET is manifested as a peculiar current step in the stability diagram due to a forbidden transition between an excited state and any of the lower energy states due to perpendicular valley (and spin) ...
Unstable relics with lifetime longer than the age of the Universe could be the dark matter today. Electrons, photons and neutrinos are a natural outcome of their decay and could be searched for in cosmic rays and in γ-ray and neutrino detectors. I compare the sensitivities of these three types of searches to the mass and lifetime of a generic unstable particle. I show that if the relics constit...
The photophysical properties of Pt(II) meso-tetrakis(4-N-methylpyridyl)porphyrin (PtTMPyP4) have been investigated in the presence of purine mononucleotides using emission and transient UV/visible/near-IR spectroscopy. While both adenosine 5'-monophosphate (AMP) and guanosine 5'-monophosphate (GMP) form 1:1 and 1:2 complexes with PtTMPyP4, the effect on the triplet lifetime is different. With A...
The recent development of Accelerator-based Gamma-induced Positron Annihilation Spectroscopy (AGPAS) has shown the possibility of probing residual stress in thick materials by Doppler broadening measurements [1]. In those measurements, the residual stresses were reflected in the line shape parameters of the 511 keV annihilation peak. However, since positron lifetime spectroscopy is a powerful t...
The lifetime of interatomic Coulombic decay (ICD) [L. S. Cederbaum et al., Phys. Rev. Lett. 79, 4778 (1997)] in Ne2 is determined via an extreme ultraviolet pump-probe experiment at the Free-Electron Laser in Hamburg. The pump pulse creates a 2s inner-shell vacancy in one of the two Ne atoms, whereupon the ionized dimer undergoes ICD resulting in a repulsive Ne+(2p(-1))-Ne+(2p(-1)) state, which...
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