Search results for "EXCITATION"
showing 10 items of 1290 documents
ChemInform Abstract: Excitation of Nucleobases from a Computational Perspective I: Reaction Paths
2016
The main intrinsic photochemical events in nucleobases can be described on theoretical grounds within the realm of non-adiabatic computational photochemistry. From a static standpoint, the photochemical reaction path approach (PRPA), through the computation of the respective minimum energy path (MEP), can be regarded as the most suitable strategy in order to explore the electronically excited isolated nucleobases. Unfortunately, the PRPA does not appear widely in the studies reported in the last decade. The main ultrafast decay observed experimentally for the gas-phase excited nucleobases is related to the computed barrierless MEPs from the bright excited state connecting the initial Franck…
Raman study of self-assembled InAs/InP quantum wire stacks with varying spacer thickness
2008
http://link.aip.org/link/?JAPIAU/104/033523/1
Lifetimes and g-factors of the HFS states in H-like and Li-like bismuth
2018
The LIBELLE experiment performed at the experimental storage ring (ESR) at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, Germany, has successfully determined the ground state hyperfine (HFS) splittings in hydrogen-like ($^{209}\rm{Bi}^{82+}$) and lithium-like ($^{209}\rm{Bi}^{80+}$) bismuth. The study of HFS transitions in highly charged ions enables precision tests of QED in extreme electric and magnetic fields otherwise not attainable in laboratory experiments. Besides the transition wavelengths the time resolved detection of fluorescence photons following the excitation of the ions by a pulsed laser system also allows to extract lifetimes of the upper HFS levels and g-fac…
Fluoreszenz‐Untersuchungen an styrylsubstituierten Benzolen
1986
Die Fluoreszenz-Abklingzeiten der stilbenartigen Verbindungen 1 – 4 zeigen, das die mittleren Lebensdauern dieser Molekule im elektronisch angeregten Singulettzustand um rund zwei Zehnerpotenzen hoher sind als bei trans-Stilben selbst. Anhand von UV-Absorptions-und Anregungsspektren wird das auf einen neu gefundenen S1-Zustand zuruckgefuhrt, der einem verbotenen Ubergang S0 S1 auf der langwelligen Seite der intensiven Absorption entspricht. Investigations on the Fluorescence of Styryl-substituted Benzenes Fluorescence decay measurements of the stilbene-like compounds 1 – 4 demonstrate that the average lifetimes of these molecules in the electronically excited singlet state are about 102 tim…
Optimization of a hot-cavity type resonant ionization laser ion source
2015
TuePS05; International audience; Resonant Ionization Laser Ion Source (RILIS) is nowadays an important technique in many RadioactiveIon Beam (RIB) facilities for its reliability and ability to ionize efficiently and element selectively.Grand Accélérateur National d’Ions Lourds (GANIL) Ion Source using Electron Laser Excitation(GISELE) is an off-line test bench for RILIS developed to study a fully operational resonant laserion source at GANIL facility. The ion source body has been designed as a modular system toinvestigate different experimental approaches by varying the design parameters, to develop the futureon-line laser ion source. The aim of this project is to determine the best technic…
Resonance ionization spectroscopy for trace analysis and fundamental research
1994
Resonance ionization spectroscopy (RIS) and its combination with mass spectrometry (RIMS) have grown to become powerful techniques, which offer high sensitivity as well as elemental and isotopic selectivity. The principles of RIS and RIMS are introduced; they primarily concern the analysis of the optical spectra for the choice of efficient excitation schemes and the suitable design of the experimental apparatus. Recent applications span from studies of short-lived isotopes at on-line mass separators to a wide variety of trace analysis applications for radioactive isotopes, which can range from measurements of solar neutrino flux to environmental assessment.
Optimal control of quantum superpositions in a bosonic Josephson junction
2012
We show how to optimally control the creation of quantum superpositions in a bosonic Josephson junction within the two-site Bose-Hubbard model framework. Both geometric and purely numerical optimal control approaches are used, the former providing a generalization of the proposal of Micheli et al [Phys. Rev. A 67, 013607 (2003)]. While this method is shown not to lead to significant improvements in terms of time of formation and fidelity of the superposition, a numerical optimal control approach appears more promising, as it allows to create an almost perfect superposition, within a time short compared to other existing protocols. We analyze the robustness of the optimal solution against at…
Measurement of laser-induced alignment of molecules by cross defocusing
2005
0146-9592; The field-free alignment of CO2 produced in response to the excitation of a molecule by a high-intensity femtosecond pump pulse is measured with a simple coronography-like technique. The technique is based on the defocusing of a time-delayed probe pulse produced by the spatial distribution of aligned molecules. In the intensity regime explored here, the technique is shown to give valuable information about dynamic alignment. With the help of simulations, the degree of alignment is extracted from the data. (C) 2005 Optical Society of America.
Multicolor upconversion luminescence of GdVO4:Ln3+/Yb3+ (Ln3+ = Ho3+, Er3+, Tm3+, Ho3+/Er3+/Tm3+) nanorods
2016
Lanthanide-doped GdVO4 nanorods that exhibit upconversion emission under 982 nm excitation have been prepared by a facile room-temperature chemical co-precipitation method followed by a subsequent annealing at temperatures of 600 degrees C, 800 degrees C and 1000 degrees C. Multicolor upconversion emission, including white, was achieved by tuning the concentrations of dopant lanthanide ions (Ho3+, Er3+, Tm3+ and Yb3+) in GdVO4. It is found that four GdVO4 samples emit light with the white chromaticity coordinates of (0.326, 0.339), (0.346, 0.343), (0.323, 0327) and (0.342, 0.340) respectively, under a single-wavelength NIR excitation. These coordinates are very close to the standard equal e…
Optimal control of the inversion of two spins in Nuclear Magnetic Resonance
2012
International audience; We investigate the optimal control of the inversion of two spin 1/2 particles in Nuclear Magnetic Resonance. The two spins, which differ by their resonance offset, are controlled by the same radio frequency magnetic field. Using the Pontryagin Maximum Principle, we compute the optimal control sequence which allows to reach the target state in a given time, while minimizing the energy of the magnetic field. A comparison with the time-optimal solution for bounded control amplitude realizing the same control in the same time is made. An experimental illustration is done using techniques of Nuclear Magnetic Resonance.