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Photoexcitation
About: Photoexcitation is a research topic. Over the lifetime, 5874 publications have been published within this topic receiving 134733 citations.
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41 citations
TL;DR: The absolute cross-section measurements for resonant double photoexcitation of Li + ions followed by autoionization have been performed at high resolution in the photon energy range from 148 eV, just below the 2s2p, 2(0, 1) + resonance, to 198 eV (the region of the double ionization threshold) as discussed by the authors.
Abstract: Absolute cross-section measurements for resonant double photoexcitation of Li + ions followed by autoionization have been performed at high resolution in the photon energy range from 148 eV, just below the 2s2p, 2(0, 1) + resonance, to 198 eV (the region of the double ionization threshold). The measurements have been made using the photon–ion merged-beam endstation at the Advanced Light Source, Lawrence Berkeley National Laboratory, USA. The absolute cross-section measurements show excellent agreement with theoretical results from the R-matrix plus pseudo-state (RMPS) method. Comparisons between theory and experiment for the Auger resonance energies, autoionization linewidth (� ) and the Fano line profile index q for several members of the principal 2snp, 2(0, 1) + and 3snp, 3(1, 1) + Rydberg series found in the photoionization spectra for the 1 P o symmetry show satisfactory accord. (Some figures in this article are in colour only in the electronic version)
41 citations
TL;DR: In this paper, it was shown that the population of excited atoms can be sensitive to both the transverse momentum and the projection of the total angular momentum of the incident radiation, which can be used to describe the photoexcitation of any atom, independent on its shell structure and number of electrons.
Abstract: The excitation of many-electron atoms and ions by twisted light has been studied within the framework of the density-matrix theory and Dirac's relativistic equation. Special attention is paid to the magnetic sublevel population of excited atomic states as described by means of the alignment parameters. General expressions for the alignment of the excited states are obtained under the assumption that the photon beam, prepared as a coherent superposition of two twisted Bessel states, irradiates a macroscopic target. We demonstrate that for this case the population of excited atoms can be sensitive to both the transverse momentum and the (projection of the) total angular momentum of the incident radiation. While the expressions are general and can be employed to describe the photoexcitation of any atom, independent on its shell structure and number of electrons, we performed calculations for the $3s\ensuremath{\rightarrow}3p$ transition in sodium. These calculations indicate that the ``twistedness'' of incoming radiation can lead to a measurable change in the alignment of the excited $^{2}P_{3/2}$ state as well as the angular distribution of the subsequent fluorescence emission.
41 citations
TL;DR: Each of the platinum-containing organometallic dimer complexes exhibits efficient nonlinear absorption of nanosecond pulses in the near-infrared region (600-800 nm), and it is demonstrated that effect is most efficient in the chromophores where the 2PA cross section maxima coincides spectrally with the excited triplet state absorption.
Abstract: A series of platinum-containing organometallic dimer complexes has been synthesized and the photophysical properties have been investigated under one- and two-photon (2PA) absorption conditions. The complexes have the general structure [DPAF−C≡C−Pt(PBu3)2−C≡C−Ar−C≡C−Pt(PBu3)2−C≡C−DPAF], where Ar is a π-conjugated unit, Bu = n-butyl, and DPAF = diphenylamino-2,7-fluorenylene. The core Ar units include 1,4-phenylene, 2,5-thienylene, 5,5′-(2,2′-bithienylene), 2,5-(3,4-ethylenedioxythiophene, 2,1,3-benzothiadiazole, and 4,7-dithien-2-yl-2,1,3-benzothiadiazole. Absorption and photoluminescence spectroscopy indicates that the complexes feature low-lying excited states based on both the core [-Pt(PBu3)2−C≡C−Ar−C≡C−Pt(PBu3)2-] chromophore as well as the DPAF units. Photoexcitation of the complexes produces a singlet state excited state, which rapidly undergos intersystem crossing to afford a triplet state that has a lifetime in the microsecond time domain. In most cases, the lowest energy triplet state is localiz...
41 citations
TL;DR: La(1/3)NbO(3):Pr(3+) is a candidate red phosphor utilizing near-UV LED chips as an excitation source and its differences in emission behavior are attributed to the energy level of the ground and excited states of 4f(2) for Pr(3+) and the trapped electron state.
Abstract: We synthesized polycrystalline pristine and Pr3+-doped perovskites La1/3MO3 (M = Nb, Ta):Pr3+ and investigated their crystal structure, optical absorption, and luminescence properties. The optical band gap of La1/3NbO3 (3.2 eV) is smaller than that of La1/3TaO3 (3.9 eV), which is primarily due to the difference in electronegativity between Nb and Ta. In La1/3NbO3:Pr3+, the red emission assigned to the f–f transition of Pr3+ from the excited 1D2 level to the ground 3H4 state upon band gap photoexcitation (near-UV) was observed, whereas the f–f transition of Pr3+ with blue-green emission from the excited 3P0 level to the ground 3H4 state was quenched. On the other hand, in La1/3TaO3:Pr3+, the blue-green emission upon band gap photoexcitation was observed. Their differences in emission behavior are attributed to the energy level of the ground and excited states of 4f2 for Pr3+, relative to the energy levels of the conduction and valence bands, and the trapped electron state, which mediates the relaxation of ...
41 citations