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We have investigated, in a previous work, the transition dipole moments (TDM) of the 13 1Σ+ states of the (SrK)+ molecular ion by using the ab initio method based on the pseudo-potential approach. The radiative lifetimes for all vibrational levels of A and C1Σ+ have been calculated by using such transition dipole moments curves. We have included the bound-free emissions probabilities further to the bound–bound transitions. The bound-free emissions probabilities have been determined exactly, using the Franck–Condon approach, and then included in the total radiative lifetime. An important change has been observed for the higher excited vibrational levels in these lifetimes when the approximate evaluation breaks down. For the first time, the radiative lifetimes associated with the Aand C1Σ+ excited state have been studied here.

Colloidal CdSe nanoplatelets (NPLs) are unique systems to study two-dimensional excitons and excitonic complexes. However, while absorption and emission of photons through exciton formation and recombination have been extensively quantified, few studies have addressed the exciton-biexciton transition. Here, we use cross-polarized pump- probe spectroscopy to measure the absorption coefficient spectrum of this transition and determine the biexciton oscillator strength (fBX). We show that fBX is independent of the NPL area and that the concomitant biexciton area (SBX) agrees with predictions of a short-range interaction model. Moreover, we show that fBX is comparable to the oscillator strength of forming localized excitons at room temperature while being unaffected itself by center-of-mass localization. These results confirm the relevance of biexcitons for light-matter interaction in NPLs. Moreover, the quantification of the exciton-biexciton transition introduced here will enable researchers to rank 2D materials by the strength of this transition and to compare experimental results with theoretical predictions.

In many applications, ranging from studies of fundamental physics to the development of future technologies, accurate atomic theory is indispensable to the design and interpretation of experiments. Direct experimental measurement of relevant parameters is often infeasible if not impossible. This paper reports the release of Version 1 of an online atomic portal for high-precision atomic data and computation that provides such information to a wide community of users. Version 1 of the portal provides transition matrix elements, transition rates, radiative lifetimes, branching ratios, hyperfine constants, quadrupole moments, and scalar and dynamic polarizabilities for atoms and ions. Version 1 includes data for the elements and ions Li, Be+, Na, Mg+, K, Ca+, Rb, Sr+, Cs, Ba+, Fr, and Ra+. The atomic properties are calculated using a high-precision, linearized coupled-cluster method. All values include estimated uncertainties. Where available, experimental values are included, with references to their sources. Data for more elements and properties will be added in the future, with alkaline earth metal atoms planned for the next release. Future updates will also include releases of user-friendly, atomic computational codes. Community input is sought to improve the portal and guide the next stages of the project. The portal includes the requisite user feedback functions for guiding future releases. A site tour and help functions allow new users to orient themselves quickly. The current portal version shows pre-computed information through an interactive interface, providing instant access to the requested data, equipped with common print and download functionality. Future versions will also allow users to request properties and elements that are rarely needed and information that has not yet been computed. Such requests will invoke the needed computations on-demand and notify the user when complete. For some requests, the response time may be a few seconds, while more advanced calculations require minutes to hours. The current implementation of the portal uses a static page design, with the data directly embedded in HTML. The pages, written in HTML, CSS, and JavaScript, are created automatically, via python scripts, from the original CSV-formatted physics data. One challenge was the representation of the denominations for electron states, such as 5f6p2 2F05/2, for which LaTeX inserts are generated. Graphs for such properties as polarizabilities make use of the Bokeh visualization package. The computational codes are written in Fortran 77/90 and have been parallelized using OpenMP for efficient execution on multicore nodes. The code runs consume significant resources, making use of concurrent runs on many nodes of the computational clusters at the University of Delaware, for the computation of properties of multiple elements simultaneously. The team includes both physicists and computer scientists, driving the design of the portal from both the physics and the software engineering angle, applying best practices for collaboration and software design.

In this work, we report on the exciton radiative lifetimes of graphitic carbon nitride monolayers in the triazine- (gC$_3$N$_4$-t) and heptazine-based (gC$_3$N$_4$-h) forms, as obtained by means of ground- plus excited-state ab initio calculations. By analysing the exciton fine structure, we highlight the presence of dark states and show that the photo-generated electron-hole pairs in gC$_3$N$_4$-h are remarkably long-lived, with an effective radiative lifetime of 260 ns. This fosters the employment of gC$_3$N$_4$-h in photocatalysis and makes it attractive for the emerging field of exciton devices. Although very long intrinsic radiative lifetimes are an important prerequisite for several applications, pristine carbon nitride nanosheets show very low quantum photo-conversion efficiency, mainly due to the lack of an efficient e-h separation mechanism. We then focus on a vertical heterostructure made of gC$_3$N$_4$-t and gC$_3$N$_4$-h layers which shows a type-II band alignment and looks promising for achieving net charge separation.

Lifetime calculations of Th II J = 1.5 and 2.5 odd states are performed with configuration&ndash, interaction many-body perturbation theory (CI-MBPT). For many J = 2.5 states, lifetimes are quite accurate, but two pairs of J = 2.5 odd states and many groups of J = 1.5 states are strongly mixed, making theoretical predictions unreliable. To solve this problem, a method based on intensities is used. To relate experimental intensities to lifetimes, two parameters, one an overall coefficient of proportionality for transition rates and one temperature of the Boltzmann distribution of populations, are introduced and fitted to minimize the deviation between theoretical and intensity-derived lifetimes. For strongly mixed groups of states, the averaged lifetimes obtained from averaged transition rates were used instead of individual lifetimes in the fit. Close agreement is obtained. Then intensity branching ratios are used to extract individual lifetimes for the strongly mixed states. The resulting lifetimes are compared to available directly measured lifetimes and reasonable agreement is found, considering limited accuracy of intensity measurements. The method of intensity-based lifetime calculations with fit to theoretical lifetimes is quite general and can be applied to many complex atoms where strong mixing between multiple states exists.

Four types of astrochemically relevant radiative processes are studied: bound-bound, bound-free, free-bound and free-free. The former two together determine radiative lifetimes, which are calculated for the HeLi+ molecular ion. Free-bound processes, also called radiative association, are studied on two systems: He in collisions with Li+ , and O in collision with C+. Collisions of He and Li+ are believed to have occurred during the recombination era of the Universe, while collisions of O with C+ are considered to be relevant in SN 1987A. Altogether, 17 radiative association cross sections and rate coefficients are calculated for radiative association, and the effect of a stimulated emission is also illustrated. A free-free process, also called radiative charge transfer, is studied in collisions of He with Li+.

We investigate the linewidths and radiative lifetimes of single InAs quantum dots embedded in the ternary matrix AlxGa(1−x)AsAlxGa(1−x)As as a function of aluminum composition. For an increasing aluminum content, we find that the average of the measured linewidths of individual transitions increases. Furthermore, we find that the distribution of the measured linewidths broadens. We infer that the linewidth broadening is the result of spectral wandering caused by inhomogeneities and local defects in the surrounding AlxGa(1−x)AsAlxGa(1−x)As matrix. Local charging and de-charging of defects polarize quantum dots in their vicinity thereby shifting the energy states of the exciton transition in time through the quantum confined Stark effect. The intrinsic radiative lifetimes of numerous quantum dots were determined. We suggest that the observed variation in radiative lifetime at a given photon energy is explained by the influence of an in-plane electric field on the oscillator strength of the electron–hole pair.

We investigate the linewidths and radiative lifetimes of single InAs quantum dots embedded in the ternary matrix AlxGa(1−x)AsAlxGa(1−x)As as a function of aluminum composition. For an increasing aluminum content, we find that the average of the measured linewidths of individual transitions increases. Furthermore, we find that the distribution of the measured linewidths broadens. We infer that the linewidth broadening is the result of spectral wandering caused by inhomogeneities and local defects in the surrounding AlxGa(1−x)AsAlxGa(1−x)As matrix. Local charging and de-charging of defects polarize quantum dots in their vicinity thereby shifting the energy states of the exciton transition in time through the quantum confined Stark effect. The intrinsic radiative lifetimes of numerous quantum dots were determined. We suggest that the observed variation in radiative lifetime at a given photon energy is explained by the influence of an in-plane electric field on the oscillator strength of the electron–hole pair.

Measurements in the time-domain of molecular chemiluminescence from CaCl(A2Π1/2, A2Π2/3, B2Σ+ →X2Σ+)and atomic resonance fluorescence from Ca(43P1→ 41S0) have been made in order to determine electronic branching ratios to yield CaCl(A1/2, A2/3, B) following the Cl-atom abstraction reaction of electronically excited calcium atoms, Ca[4s4p(3PJ)] , 1.888 eV above the 4s2(1S0) ground state, with CH3Cl. Ca[4s4p(3P1)] was generated by the pulsed dye-laser excitation ofground state calcium atoms at λ = 657.3 nm 21, {Ca[4s4p(n3P1)] ←Ca[4s2(1S0)]} at elevated temigeratures in the presence of CH3Cl and excess helium buffer gas in a slow flow system, kinetically equivalent to a static system. Atomic and molecular emissions were recorded following rapid Boltzmann equilibration within the Ca(43P0,1.2) spin-orbit manifold, atomic emission being restricted to the 3P1 state as the 3P0 and 3P2 states are long-lived, being so called ‘reservoir states’. Atomic fluorescence emission profiles at the resonance wavelength together with the molecular chemiluminescence emissions CaCl (A2Π1/2→X2Σ+, Δν=0, λ=621nm),CaClA2Π3/2→X2Σ+, Δν=0, λ=618nm and CaCl(B2Σ+→X2Σ+, Δν=0, λ=593nm) were recorded. The atomic and molecular emissions demonstrated exponential decays characterised by decay coefficients which were equal under identical chemical conditions thus demonstrating the production of CaCl(A2Π1/2,3/2, B2Σ+) by direct reaction of Ca(3pJ) with CH3Cl. The combination of the time-dependences of the atomic and molecular profiles as a function of the concentration of CH3Cl together with the integrated atomic and molecular intensities, placed on a common intensity scale by calibration of the optical system against a spectral radiometer, yielded branching ratios into the A2Π1/2, A2Π3/2 and B2Σ+ states of CaCl. These were found to be as follows: A1/ (2.6±1.1)2×10−3; A2/3(1.9±0.8)×10−3 and B(3.6±2.0)×10−4. To the best of our knowledge, these data represent the first measurements of electronic branching ratios of calcium chlorides into specific molecular states for reactions of Ca(3pJ) determined in the time-domain. The results are compared with various related data for total branching ratios into electronic states studied in the single collision condition for this atomic state with CH3Cl using molecular beams. These are also compared with branching ratios of SrCl(A2Π1/2, A2Π2/3, B2Σ+) following the reaction of Sr[5s5p(3pJ)]+ CH2Cl2 investigated following pulsed dye-laser excitation where the yields of SrCl(A1/2, A3/2, B)were of similar low magnitudes.

The Einstein coefficients and radiative lifetimes for diatomic molecules such as N-2 and CO have been computed using the Fourier Grid Hamiltonian (FGH) method and a comparison with other methods has been made. The Hamiltonian matrix is constructed using the Hulburt and Hirschfelder (HH) potential model and the Rydberg-Klein-Rees (RKR) potential model for diatomic molecules. The FGH method works well for any model of the potential including the tabulated forms of experimental potential energy data. The eigenvalues and vibrational wave-functions for the ground and the exited state of N-2 and CO molecules have been computed by diagonalizing the Hamiltonian matrix. The vibrational wave-functions and eigenvalues for the ground and the excited states are used to calculate the radiative transition parameters such as Einstein coefficients (A(v '' v')), radiative lifetimes, electronic transition dipole moments (R-e(x)), Franck-Condon factors (FCFs), r-Centroids and average internuclear separations for both the models. FGH method work well for both the models. There are good agreements between our computed values of radiative transition parameters for both the models and the values estimated by other methods. (C) 2015 Elsevier B.V. All rights reserved.

We report new experimental Fe I oscillator strengths obtained by combining measurements of branching fractions measured with a Fourier Transform spectrometer and time-resolved, laser-induced fluorescence lifetimes. This study covers the spectral region ranging from 213 to 1033 nm. A total of 120 experimental log( ) gf -values coming from 15 odd-parity energy levels are provided, 22 of which have not been reported previously and 63 of which have values with lower uncertainty than the existing data. The radiative lifetimes for 60 upper energy levels are presented, 39 of which have no previous measurements.

We determine Mg abundances in 6 Gaia benchmark stars using theoretical one-dimensional (1D) hydrostatic model atmospheres, as well as temporally- and spatially-averaged 3D model atmospheres (). The stars cover a range of Teff from 4700 to 6500 K, log g from 1.6 to 4.4 dex, and [Fe/H] from -3.0 dex to solar. Spectrum synthesis calculations are performed in local thermodynamic equilibrium (LTE) and in non-LTE (NLTE) using the oscillator strengths recently published by Pehlivan Rhodin et al. We find that: a) Mg abundances determined from the infrared spectra are as accurate as the optical diagnostics, b) the NLTE effects on Mg I line strengths and abundances in this sample of stars are minor (although for a few Mg I lines the NLTE effects on abundance exceed 0.6 dex in and 0.1 dex in 1D, c) the solar Mg abundance is 7.56 +/- 0.05 dex (total error), in the excellent agreement with the Mg abundance measured in CI chondritic meteorites, d) the 1D NLTE and NLTE approach can be used with confidence to analyse optical Mg I lines in spectra of dwarfs and sub-giants, but for red giants the Mg I 5711 A line should be preferred, e) low-excitation Mg I lines are sensitive to the atmospheric structure; for these lines, LTE calculations with models lead to significant systematic abundance errors. The methods developed in this work will be used to study Mg abundances of a large sample of stars in the next paper in the series., 25 pages, accepted for publication in ApJ

The lifetimes of 17 even-parity levels (3d5s, 3d4d, 3d6s, and 4p$^2$) in the region 57743-77837 cm$^{-1}$ of singly ionised scandium (\ion{Sc}{ii}) were measured by two-step time-resolved laser induced fluorescence spectroscopy. Oscillator strengths of 57 lines from these highly excited upper levels were derived using a hollow cathode discharge lamp and a Fourier transform spectrometer. In addition, Hartree--Fock calculations where both the main relativistic and core-polarisation effects were taken into account were carried out for both low- and high-excitation levels. There is a good agreement for most of the lines between our calculated branching fractions and the measurements of Lawler and Dakin (1989) in the region 9000-45000 cm$^{-1}$ for low excitation levels and with our measurements for high excitation levels in the region 23500-63100 cm$^{-1}$. This, in turn, allowed us to combine the calculated branching fractions with the available experimental lifetimes to determine semi-empirical oscillator strengths for a set of 380 E1 transitions in \ion{Sc}{ii}. These oscillator strengths include the weak lines that were used previously to derive the solar abundance of scandium. The solar abundance of scandium is now estimated to $\log~\epsilon_\odot = 3.04\pm0.13$ using these semi-empirical oscillator strengths to shift the values determined by Scott et al. (2015). The new estimated abundance value is in agreement with the meteoritic value ($\log~\epsilon_{\text{met}}=3.05\pm0.02$) of Lodders et al. (2009)., Comment: Accepted for publication in MNRAS on 18 August 2017, https://doi.org/10.1093/mnras/stx2159

In this work we investigate light matter interaction at the nanoscale. We focus on zero-dimensional objects, dubbed quantum dots, which are compositional defined nanometer-sized semiconductor structures in which charge carriers are spatially confined in all three dimensions. Using a tunable laser source, we can selectively address a few quantum dots in order to collect and analyze their photoluminescence spectrum. The aim is to probe the radiative recombination dynamics of the electron–hole pair created inside the quantum dot, which constitutes the exciton, and study the interaction with its environment. The charge fluctuations in the close neighborhood of the quantum dot are studied at low temperatures, when the influence of lattice vibrations is minimized. Besides the radiative broadening, the optical transition linewidth reflects the amount of changes in electric field caused by the charging and de-charging of local defects. This is a dynamical process, which is referred to as spectral diffusion or spectral wandering. On the other hand, the quantum dot static electrical environment is studied when an ultrafast pulsed laser source in combination with an ultra sensitive detector are employed. From these measurements, we can determine the radiative recombination time of the exciton. This recombination time reflects the coherence time of the electron and hole inside the quantum dot, which is important for quantum optoelectronic operation processes.Another important aspect of the interaction between the exciton inside the quantum dot and its environment is the influence of lattice vibrations caused by thermally activated oscillations of the surrounding atoms. When the temperature is raised their role will become more apparent and the dynamics can be studied. We found that the linewidth broadening of self-assembled InAs quantum dots inside an AlxGa(1−x)As matrix at low temperature is determined solely by the spectral wandering rather than the radiative broadening process. We infer that the spectral wandering is caused by local charge defects that are created at the InAs wetting layer to AlxGa(1−x)As matrix interface. Furthermore, the radiative lifetime of the exciton is dispersed at a given photon energy as a result of the in-plane electric field that is created by the local charge traps.In this work, we also explore the blooming field of nanoplasmonics, which studies the electromagnetic field interaction with a reservoir of free electrons inside a metal at the nanoscale. We place metal nanoparticles in close proximity to the quantum dot where they act as optical resonators. The exciton wave function can couple radiatively to an external cavity to enhance the oscillator strength of the electron-hole transition. The idea behind the experiments is to sufficiently increase the internal quantum efficiency of the quantum dot and metal nanoparticle system, thereby establishing device operation up to room temperature. Lithography techniques were employed to create the structures necessary to perform the measurements. We used a shallow etching technique to create freestanding nanomesas that contain the quantum dot layer. Subsequently, colloidal gold metal nanoparticles were deposited on the substrate surface where they tend to stick to the mesas by means of adhesive forces. Although the radiative enhancement is moderate at low temperatures, we were able to establish radiative coupling between the quantum dots and nanoparticles.

In this work we investigate light matter interaction at the nanoscale. We focus on zero-dimensional objects, dubbed quantum dots, which are compositional defined nanometer-sized semiconductor structures in which charge carriers are spatially confined in all three dimensions. Using a tunable laser source, we can selectively address a few quantum dots in order to collect and analyze their photoluminescence spectrum. The aim is to probe the radiative recombination dynamics of the electron–hole pair created inside the quantum dot, which constitutes the exciton, and study the interaction with its environment. The charge fluctuations in the close neighborhood of the quantum dot are studied at low temperatures, when the influence of lattice vibrations is minimized. Besides the radiative broadening, the optical transition linewidth reflects the amount of changes in electric field caused by the charging and de-charging of local defects. This is a dynamical process, which is referred to as spectral diffusion or spectral wandering. On the other hand, the quantum dot static electrical environment is studied when an ultrafast pulsed laser source in combination with an ultra sensitive detector are employed. From these measurements, we can determine the radiative recombination time of the exciton. This recombination time reflects the coherence time of the electron and hole inside the quantum dot, which is important for quantum optoelectronic operation processes. Another important aspect of the interaction between the exciton inside the quantum dot and its environment is the influence of lattice vibrations caused by thermally activated oscillations of the surrounding atoms. When the temperature is raised their role will become more apparent and the dynamics can be studied. We found that the linewidth broadening of self-assembled InAs quantum dots inside an AlxGa(1−x)As matrix at low temperature is determined solely by the spectral wandering rather than the radiative broadening process. We infer that the spectral wandering is caused by local charge defects that are created at the InAs wetting layer to AlxGa(1−x)As matrix interface. Furthermore, the radiative lifetime of the exciton is dispersed at a given photon energy as a result of the in-plane electric field that is created by the local charge traps. In this work, we also explore the blooming field of nanoplasmonics, which studies the electromagnetic field interaction with a reservoir of free electrons inside a metal at the nanoscale. We place metal nanoparticles in close proximity to the quantum dot where they act as optical resonators. The exciton wave function can couple radiatively to an external cavity to enhance the oscillator strength of the electron-hole transition. The idea behind the experiments is to sufficiently increase the internal quantum efficiency of the quantum dot and metal nanoparticle system, thereby establishing device operation up to room temperature. Lithography techniques were employed to create the structures necessary to perform the measurements. We used a shallow etching technique to create freestanding nanomesas that contain the quantum dot layer. Subsequently, colloidal gold metal nanoparticles were deposited on the substrate surface where they tend to stick to the mesas by means of adhesive forces. Although the radiative enhancement is moderate at low temperatures, we were able to establish radiative coupling between the quantum dots and nanoparticles.

In this work we investigate light matter interaction at the nanoscale. We focus on zero-dimensional objects, dubbed quantum dots, which are compositional defined nanometer-sized semiconductor structures in which charge carriers are spatially confined in all three dimensions. Using a tunable laser source, we can selectively address a few quantum dots in order to collect and analyze their photoluminescence spectrum. The aim is to probe the radiative recombination dynamics of the electron–hole pair created inside the quantum dot, which constitutes the exciton, and study the interaction with its environment. The charge fluctuations in the close neighborhood of the quantum dot are studied at low temperatures, when the influence of lattice vibrations is minimized. Besides the radiative broadening, the optical transition linewidth reflects the amount of changes in electric field caused by the charging and de-charging of local defects. This is a dynamical process, which is referred to as spectral diffusion or spectral wandering. On the other hand, the quantum dot static electrical environment is studied when an ultrafast pulsed laser source in combination with an ultra sensitive detector are employed. From these measurements, we can determine the radiative recombination time of the exciton. This recombination time reflects the coherence time of the electron and hole inside the quantum dot, which is important for quantum optoelectronic operation processes. Another important aspect of the interaction between the exciton inside the quantum dot and its environment is the influence of lattice vibrations caused by thermally activated oscillations of the surrounding atoms. When the temperature is raised their role will become more apparent and the dynamics can be studied. We found that the linewidth broadening of self-assembled InAs quantum dots inside an AlxGa(1−x)As matrix at low temperature is determined solely by the spectral wandering rather than the radiative broadening process. We infer that the spectral wandering is caused by local charge defects that are created at the InAs wetting layer to AlxGa(1−x)As matrix interface. Furthermore, the radiative lifetime of the exciton is dispersed at a given photon energy as a result of the in-plane electric field that is created by the local charge traps. In this work, we also explore the blooming field of nanoplasmonics, which studies the electromagnetic field interaction with a reservoir of free electrons inside a metal at the nanoscale. We place metal nanoparticles in close proximity to the quantum dot where they act as optical resonators. The exciton wave function can couple radiatively to an external cavity to enhance the oscillator strength of the electron-hole transition. The idea behind the experiments is to sufficiently increase the internal quantum efficiency of the quantum dot and metal nanoparticle system, thereby establishing device operation up to room temperature. Lithography techniques were employed to create the structures necessary to perform the measurements. We used a shallow etching technique to create freestanding nanomesas that contain the quantum dot layer. Subsequently, colloidal gold metal nanoparticles were deposited on the substrate surface where they tend to stick to the mesas by means of adhesive forces. Although the radiative enhancement is moderate at low temperatures, we were able to establish radiative coupling between the quantum dots and nanoparticles.

The photoluminescence (PL) at low temperature of three delta-doped AlGaAs/GaAs heterostructures is investigated under continuous and pulsed excitations. The PL under continuous excitations allows the identification of the trapping centres and probes the carrier's transfer to the GaAs channel. The time-resolved photoluminescence (TRPL) inquires about carrier dynamics and gives radiative lifetimes of different levels. The DX level shows two time constants of the intensity decay relating the splitting of the valence band under impurity strains which reduce the crystal symmetry. The two time constants evolve with temperature and exhibit an increase near T = 50 K. (c) 2008 Elsevier B.V. All rights reserved.

The photophysical properties of porphyrins with N3S and N3O cores appended with two boron-dipyrrin units and porphyrins with N2S2 and N4 cores appended with four boron-dipyrrin units are described. The steady-state fluorescence measurements indicate that the energy transfer from boron-dipyrrin units to the porphyrin unit is efficient with N4 and N3O porphyrin cores and less efficient with N3S and N2S2 cores. The energy transfer rates calculated from lifetime measurements are also in support with these observations., © Elsevier

A systematic study of exciton dynamics is presented in quantum boxes formed naturally along the axis of a V-shaped quantum wire, by means of time and spatially resolved resonant photoluminescence. The dependence of radiative lifetimes and relaxation mechanisms of excitons is determined versus the size of the boxes. The radiative recombination rate varies linearly with the length of the box, showing that the exciton has a coherence volume equal to the volume of the box. In a low excitation regime, emission from excited states has not been observed, which would be a consequence of relaxation bottleneck, but there is clear evidence that relaxation via emission of LA phonons depends strongly on the energy separation between the different quantum box levels.

The spectral transitions and the character of the low-lying excited states of the copper halides, CuX (X = Cl, Br, I) are studied by means of two different relativistic computational approaches. One is based on the CASSCF/CASPT2 approach with operators accounting for scalar relativistic effects evaluated as a first order correction to the CASSCF energy. The other is a fully relativistic four component SCF-CI treatment based on the Dirac-Coulomb Hamiltonian and hence accounts intrinsically for spin-orbit coupling as well as for scalar effects. The lowest excited states ((1,3)Sigma(+), (1,3)Pi, (1,3)Delta) are all closely related to the formal ionic configuration Cu+(3d(9)4s(1)) X-(ns(2)np(6)). The agreement between calculated and measured transition energies and transition dipoles and their trends in the series strengthens recent assignments of the observed bands. Unobserved 'neutral' states, dominated by the configuration Cu(3d(10)4s(1)) X(ns(2)np(5)), are situated mostly far above the 'ionic' states. Particular attention was given to the mixing of these states, i.e. to the importance of charge transfer effects in the description of the observed states. These seem to be of significance only for the (1) Sigma(+) states, judging from the weights of the charge transfer configurations in the total wave functions and the character of the open shell orbitals. The calculated increase in charge transfer on going from Cl to I in the series goes together with an increase in the calculated transition dipoles for the (1) Sigma(+) states. This is consistent with the observed decrease of the lifetimes. The magnitudes of the spin-orbit splittings in the ionic states are governed by the splitting in Cu+ (2000 cm(-1)) as expected.

The character of the low-lying excited states of diatomic CuCl is studied primarily by means of the complete active space self-consistent field (CASSCF), method and a second order perturbation approach with the CASSCF wave function as reference state [complete active space perturbation theory to second order (CASPT2)]. Far comparison, the lower levels of the spectra of the Cu+ ion are also analyzed. A first order treatment of the scalar relativistic effects, the mass-velocity and Darwin terms, is included in the calculations. The importance of spin-orbit interactions is investigated by comparing our nonrelativistic valence shell CI (VCI) and relativistic results obtained with our four-component program suite MOLFDIR. The six lowest excited states of the CuCl molecule, which are related to the Cu+(3d(9)4s(1))Cl-(3s(2)3p(6)) ionic configuration, are assigned. The assignments agree with earlier theoretical work. Where they can be compared, the calculated spectroscopic constants are in good agreement with the experimental data. (C) 1997 American Institute of Physics.

Complementary tests of the partially correlated speed-dependent Keilson-Storer (pCSDKS) model for the shape of isolated transition of pure water vapor[N. H. Ngo et al. , J. Chem. Phys.136, 154310 (Year: 2012)]10.1063/1.4704675 are made using new measurements. The latter have been recorded using a high sensitivity cavity ring down spectrometer, for seven self-broadened H2O lines in the 1.6 μm region at room temperature and for pressures from 0.5 to 15 Torr. Furthermore, the H2 18O spectra of [M. D. De Vizia et al. , Phys. Rev. A83, 052506 (Year: 2011)]10.1103/PhysRevA.83.052506 in the 1.38 μm region, measured at 273.15 K and for pressures from 0.3 to 3.75 Torr have also been used for comparison with the model. Recall that the pCSDKS model takes into account the collision-induced velocity changes, the speed dependences of the broadening and shifting coefficients as well as the partial correlation between velocity and rotational-state changes. All parameters of the model have been fixed at values previously determined, except for a scaling factor applied to the input speed-dependent line broadening. Comparisons between predictions and experiments have been made by looking at the results obtained when fitting the calculated and measured spectra by Voigt profiles. The good agreement obtained for all considered lines, at different temperature and pressure conditions, confirms the consistency and the robustness of the model. Limiting cases of the model have been then derived, showing the influence of different contributions to the line shape.

We have directly observed the localization dynamics of excitons within growth islands of a GaAs/Al0.17Ga0.83As single quantum well by time-resolved photoluminescence (PL). The PL emission of each growth island is split into two peaks that have an energy separation of 3 meV. These peaks are attributed to the emission of free and localized excitons within the islands. Upon pulsed excitation, the high-energy free-exciton PL line dominates the initial emission, while for longer times (350 ps) the bound-exciton PL peak emerges. This observation directly reflects the localization of free excitons within the growth islands.

Semipolar {n[n¯]01} InGaN/GaN quantum wells (QWs) (n = 1−3) are fabricated on top of GaN microstructures, which consist of semipolar {1Ī01} facets. Semipolar planes are obtained via regrowth of three-dimensional structures on (0001) GaN templates under controlled growth conditions. Compared to QWs on {1Ī01} facets, {n[n¯]01} ridge QWs show an intense emission at ∼ 440 nm. Time resolved photoluminescence reveals that the radiative lifetime of excitons in {n[n¯]01} InGaN ridge QWs at 13 K is 310 ps, which is comparable to that in {1Ī01} QWs. The estimated internal quantum efficiency at room temperature is as high as 57%.

International audience; Both weakly and strongly confined excitons are studied by time-resolved photoluminescence in a nonpolar nitride-based heterostructure grown by molecular beam epitaxy on the a-facet of a bulk GaN crystal, with an ultralow dislocation density of 2 × 105 cm−2. Strong confinement is obtained in a 4 nm thick Al0.06Ga0.94N/GaN quantum well (QW), whereas weakly confined exciton-polaritons are observed in a 200 nm thick GaN epilayer. Thanks to the low dislocation density, the effective lifetime of strongly confined excitons increases between 10 and 150 K, proving the domination of radiative recombination processes. Above 150 K theQWemission lifetime diminishes, whereas the decay time of excitons in the barriers increases, until both barrier and QW exciton populations become fully thermalized at 300 K. We conclude that the radiative efficiency of our GaN QW at 300 K is limited by nonradiative recombinations in the barriers. The increase of exciton-polariton coherence lengths caused by low dislocation densities allows us to observe and model the quantized emission modes in the 200 nm nonpolar GaN layer. Finally, the low-temperature phonon-assisted relaxation mechanisms of such center-of-mass quantized exciton-polaritons are described.

4 pags. ; 2 figs., Recently, the predissociation lifetimes of the NeBr2(B) complex for different initial vibrational excitation (10 ≤ v′ ≤ 20) have been measured using time-resolved optical pump-probe spectroscopy [ Taylor et al., J. Chem. Phys., 132, 104309 (2010) ]. In the vibrational interval studied, the vibrational predissociation (VP) proceeds by the transfer of a single vibrational quantum and the lifetimes are expected to decrease smoothly with increasing v′, as predicted by the energy gap law. However, the experimental lifetimes show strong oscillations with v′, which were attributed to the occurrence of electronic predissociation into two possible dissociative electronic states of Br2(1g,2g), based on a Franck–Condon spectator model. In this work we reproduce the experimental findings by performing full three-dimensional wave packet calculations for the competition of vibrational and electronic predissociation, including the B(0u+), 2g, and C(1u) electronic states. Model potential energy surfaces were used based on previous theoretical simulations of the VP dynamics on the B state and on ab initio calculations on the NeCl2 related system. Thus, only two parameters, the strength of the electronic couplings, are fit to achieve the excellent theoretical/experimental agreement., This work has been supported by the Ministerio de Ciencia e Innovación under Project No. CTQ2007-62898 and U.S. National Science Foundation Grant No. CHE-0404743. The calculations have been performed in the IFF and CESGA computing centers.

The ab initio calculation has been carried out to study the astrophysically important forbidden electromagnetic transition rates of singly ionized zinc (Zn II). Electron correlations are considered to all orders using coupled-cluster theory in the relativistic framework. Calculated excitation energies are in excellent agreement with the experimental values, wherever available. Forbidden transition rates due to the magnetic dipole and electric quadrupole transitions are estimated for the first time in the literature, to our knowledge. These transitions span the range of ultraviolet, visible and near infrared regions, and are crucial for astrophysical observations.

We evaluated the radiative lifetimes and the one-dimensional exciton coherence lengths in single-walled carbon nanotubes (SWNTs). The radiative lifetimes determined from simultaneous measurements of photoluminescence (PL) lifetimes and PL quantum yields range from ~3 to 10 ns, and slightly increase with the tube diameter. The exciton coherence lengths in SWNTs are of the order of 10 nm, as deduced from the experimentally obtained radiative lifetimes, and they are about ten times larger than the exciton Bohr radius along the tube axis.

Using the relativistic coupled-cluster method, we have calculated ionization potentials, E1 matrix elements and dipole polarizabilities of many low-lying states of Ca$^+$. Contributions from the Breit interaction are given explicitly for these properties. Polarizabilities of the ground and the first excited d-states are determined by evaluating the wave functions that are perturbed to first order by the electric dipole operator and the black-body radiation shifts are estimated from these results. We also report the results of branching ratios and lifetimes of the first excited p-states using both the calculated and experimental wavelengths and compare them with their measured values., Comment: 10 pages, 1 figure

Ab initio calculations reveal that radiative lifetime of the lowest excited singlet state of 2-aminopyridine (2AP) molecule should be around 20 ns, consistent with the molecules of the same type, but is about one order of magnitude larger than the claimed experimental fluorescent lifetime in recent years. A S1/S0 conical intersection close to the S1 state has been located which could be the possible nonradiative channel that is responsible for the fast decay observed in the experiment. QC20100719 Copyright (2009) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics

We report microphotoluminescence spectroscopy performed on individual and ensemble InGaN/GaN quantum disks (Q-disks). The typical spectrum of a single Q-disk exhibited the contribution of localization centers (LCs) formed in the InGaN active layer of the Q-disks, characterized by sharp lines appearing on the low energy side of the spectra. In addition, a broader emission peak identified as the luminescence of the quasi-two-dimensional (2D) InGaN active layer surrounding the LCs appears systematically at higher energy. Time-resolved photoluminescence experiment performed on single Q-disks exhibited the excitonic transfer, from the 2D InGaN active layer to LCs, at the submicroscopic scale. Excitation power dependence studies and linear polarization analysis allowed us to identify a biexciton complex confined in a LC in a single Q-disk with a surprising positive binding energy of 13 meV. The absence of screening effect by increasing the excitation power density and the fast excitonic radiative lifetime of a few hundred picoseconds that we measured on several individual Q-disks indicate that the absence of internal electric field in the structure can explain the observed positive biexciton binding energy.

First laser cooling and trapping of the heavy alkaline earth element barium has been achieved based on the strong 6s$^2$ $^1$S$_0$ - 6s6p $^1$P$_1$ transition for the main cooling. Due to the large branching into metastable D-states several additional laser driven transitions are required to provide a closed cooling cycle. A total efficiency of $0.4(1) \cdot 10^{-2}$ for slowing a thermal atomic beam and capturing atoms into a magneto optical trap was obtained. Trapping lifetimes of more than 1.5 s were observed. This lifetime is shortened at high laser intensities by photo ionization losses. The developed techniques will allow to extend significantly the number of elements that can be optically cooled and trapped., Comment: 4 pages, 5 figures

We have carried out continuous wave and time resolved photoluminescence experiments in self-assembled In(Ga)As quantum dots and quantum rings embedded in field effect structure devices. In both kinds of nanostructures, we find a noticeable increase of the exciton radiative lifetime with the external voltage bias that must be attributed to the field-induced polarizability of the confined electron hole pair. The interplay between the exciton radiative recombination and the electronic carrier tunneling in the presence of a stationary electric field is therefore investigated and compared with a numerical calculation based on the effective mass approximation., The authors gratefully acknowledge financial support by the Spanish MEC and CAM through Projects Nos.TEC-2005-05781-C03-01/03, NAN2004-09109-C04-01/03,CSD2006-0019, and S-505/ESP/000200, and by the European Commission through the SANDIE Network of Excellence (Contract No. NMP4-CT-2004-500101).

A photoluminescence study of self-assembled InAs/GaAs quantum dots under the influence of magnetic fields perpendicular and parallel to the dot layer is presented. At low temperatures, the magnetic field perpendicular to the dot layer alters the in-plane transport properties due to localization of carriers in wetting layer (WL) potential fluctuations. Decreased transport in the WL results in a reduced capture into the quantum dots and consequently a weakened dot-related emission. The effect of the magnetic field exhibits a considerable dot density dependence, which confirms the correlation to the in-plane transport properties. An interesting effect is observed at temperatures above approximately 100 K, for which magnetic fields, both perpendicular and parallel to the dot layer, induced an increment of the quantum dot photoluminescence. This effect is ascribed to the magnetic confinement of the exciton wave function, which increases the probability for carrier capture and localization in the dot, but affects also the radiative recombination with a reduced radiative lifetime in the dots under magnetic compression. Original Publication:Mats Larsson, Evgenii Moskalenko, Andréas Larsson, Per-Olof Holtz, C. Verdozzi, C.-O. Almbladh, W. V. Schoenfeld and P. M. Petroff, Magnetic field effects on optical and transport properties in InAs/GaAs quantum dots, 2006, Physical Review B, (74), 245312.http://dx.doi.org/10.1103/PhysRevB.74.245312Copyright: American Physical Societyhttp://www.aps.org/

We investigate the linear optical properties and energy transfer processes in tungstate fluorophosphate glass doped with thulium (Tm3+) and neodymium (Nd3+) ions. The linear absorption spectra from 370to3000nm were obtained. Transitions probabilities, radiative lifetimes, and transition branching ratios were determined using the Judd-Ofelt [Phys. Rev. 127, 750 (1962); J. Chem. Phys. 37, 511 (1962)] theory. Frequency up-conversion to the blue region and fluorescence in the infrared were observed upon pulsed excitation in the range of 630–700nm. The excitation spectra of the luminescence were obtained to understand the origin of the signals. The temporal decay of the fluorescence was measured for different concentrations of the doping ions. Energy transfer rates among the Tm3+ and Nd3+ ions were also determined.We investigate the linear optical properties and energy transfer processes in tungstate fluorophosphate glass doped with thulium (Tm3+) and neodymium (Nd3+) ions. The linear absorption spectra from 370to3000nm were obtained. Transitions probabilities, radiative lifetimes, and transition branching ratios were determined using the Judd-Ofelt [Phys. Rev. 127, 750 (1962); J. Chem. Phys. 37, 511 (1962)] theory. Frequency up-conversion to the blue region and fluorescence in the infrared were observed upon pulsed excitation in the range of 630–700nm. The excitation spectra of the luminescence were obtained to understand the origin of the signals. The temporal decay of the fluorescence was measured for different concentrations of the doping ions. Energy transfer rates among the Tm3+ and Nd3+ ions were also determined.

Individual rotational levels in the A1A2,v4 = 1 state of thioformaldehyde (H2CS) are excited by a cw laser and microwave transitions in the region of 8–12 GHz are measured. Some of the microwave frequencies are found to be characteristic of rotational levels other than the level being pumped. Since the microwave frequencies are characteristic of individual rotational levels in the excited state and the excited-state lifetime is ∼ 170 μs, information is obtained concerning rotational selection rules during collisions. It is found that J can change by several units and Ka by 0, ±2, ±4, and ±6. The latter result confirms that o-H2CS is not converted to p-H2CS by collisions. Observation of Ka doublets indicates that there are no appreciable differences between the two components.indicates that there are no appreciable differences between the two components.

We present a theoretical model of the time-resolved excitonic photoluminescence in quantum wires. We study the role of disorder and of the exciton-free-carrier interaction on the temperature dependence of the photoluminescence lifetime. We find that at low temperature the exciton population is not thermalized in disordered quantum wires and that the lifetime is mainly determined by the localization length of the exciton. However, for large localization lengths or high enough temperatures the exciton population thermalizes within its lifetime and the temperature dependence becomes square-root-like. The inclusion of free carriers leads to an increase of the lifetime at high temperatures and to a quasiexponential temperature dependence.

We have observed the pH-dependent formation of electrostatic complexes of chlorin p6 with surfactants in submicellar concentrations. Successive protonation of the ionizable groups cause a progressively increasing positive charge on the fluorophore as the pH decreases. Complexes are formed with the cationic CTAB at pH 7 and 5 and with the anionic SDS at pH 3, as manifested in a decrease in fluorescence quantum yield and radiative lifetime at low surfactant concentrations. The fluorescence quantum yield and lifetime are observed to increase beyond certain concentrations of the surfactants and saturate before the critical micellar concentrations are reached. The variation in the fluorescence parameters is rationalized by a competitive model involving pH-induced and surfactant-induced aggregates., © Elsevier

10 pages; Two-photon excitation of a quantum ladder system by an ultrashort chirped pulse leads to interferences in the excited-state population, between direct and sequential paths. Experimental results have been obtained in atomic sodium vapor. The presence of several intermediate and final states leads to new phenomena. The interplay between the two sequential paths leads to strongly contrasted oscillations and a large enhancement of the transition probability for precise values of the chirp. A cubic spectral phase modifies significantly the behavior of the quantum interferences and can be used to enhance the two-photon absorption rate.

We model the optical dynamics in linear Frenkel exciton systems governed by scattering on static disorder and lattice vibrations, and calculate the temperature dependent fluorescence spectrum and lifetime. The fluorescence Stokes shift shows a nonmonotonic behavior with temperature, which derives from the interplay of the local band-edge level structure and thermal equilibration. The model yields excellent fits to experiments performed on linear dye aggregates., Comment: 4 pages, 3 figures

7 pages; International audience; Different lifetime broadenings in molecular-field-split 2p core levels in H2S are predicted theoretically and are identified in an experimental investigation of the S 2p Auger electron spectrum. The measurements were performed for the transition to the vibrationally resolved X1A1 ground state of H2S2+. The lifetimes of the 3e1/2 and 5e1/2 levels of the 2p ionized molecule are found to be 64 and 74 meV, respectively. This unambiguous determination of the lifetime difference of 10±1 meV is only possible as the 4e1/2→X1A1(2b1-2) decay channel that overlaps the 5e1/2→X1A1(2b1-2) channel is practically suppressed in Auger decay in H2S. The lifetime difference is confirmed by ab initio calculations. A theoretical analysis shows that it results from the mutual orientation of the core hole in the intermediate states and the valence electron density in the sulfur 3p orbitals. Both are strongly influenced by the chemical bond. Thus the observed effect is the direct result of a fundamental property of molecular electronic structure.

The exciton localization is studied in GaAs/GaAlAs V-shaped quantum wires (QWRs) by high spatial resolution spectroscopy. Scanning optical imaging of different generations of samples shows that the localization length has been enhanced as the growth techniques were improved. In the best samples, excitons are delocalized in islands of length of the order of 1 micron, and form a continuum of 1D states in each of them, as evidenced by the sqrt(T) dependence of the radiative lifetime. On the opposite, in the previous generation of QWRs, the localization length is typically 50 nm and the QWR behaves as a collection of quantum boxes. These localization properties are compared to structural properties and related to the progresses of the growth techniques. The presence of residual disorder is evidenced in the best samples and explained by the separation of electrons and holes due to the large in-built piezo-electric field present in the structure., 8 figures

International audience; Luminescence, decay, and thermal quenching under photonic excitation of CaGa2S4:Eu2+ mono and polycrystals have been measured. For excitation into the lower 5d states, thermal quenching starts above 350 K, which makes this material appropriate for use as a yellow phosphor under excitation by blue-emitting diodes. Thermoluminescence after 337.1 nm irradiation is explained by photoionization of Eu2+ ions.

Summary form only given. In recent years, there have been enormous research efforts to improve the performance of lasers emitting at 3 /spl mu/m mainly because of their potential applications in laser surgery. Due to the high absorption of 3-/spl mu/m radiation in water, high-quality cutting or ablation is demonstrated in biological tissue using erbium-doped solid-state lasers. We have recently demonstrated a CW output power of 17 W at 2.7 /spl mu/m with a slope efficiency of 17% from an Er/sup 3+/,Pr/sup 3+/ codoped ZBLAN fiber. In this paper, we investigate whether energy recycling by energy-transfer upconversion (ETU) from the lower laser level with its inherent enhancement of the slope efficiency by a factor of 2 can operate this fiber laser more efficiently than lifetime quenching of the lower laser level by the Pr/sup 3+/ codopant.

International audience; In transmission metallic gratings, quasi-total transmission of light is achieved by two different mechanisms, which are the excitation of horizontal and vertical surface-plasmon resonances. Both resonances are represented on complex photonic band structures for a wide range of grating thicknesses. The evolution of the electromagnetic field intensity provides a physical understanding of the behaviour of dispersion curves and of lifetime discontinuities in Wood-Rayleigh anomalies in particular. Both radiative and non-radiative processes are distinguished in the resonances' width, giving limits for the use of metallic gratings in photonic devices.

We present a continuous-wave and time-resolved magnetoluminescence investigation of InxGa1-xAs V-shaped quantum wires (QWR's) with In content x = 0.1, 0.15, 0.2. The diamagnetic shifts and the field dependence (up to 8 T) of the recombination lifetime show a competition between exciton and free-carrier processes. In QWR's with low In content (x = 0.1) the observed increase of the photoluminescence decay time with the magnetic field is explained by a theoretical calculation of free-carrier recombination. In-rich QWR's exhibit instead a decrease of the decay time at low temperature, which is characteristic of the exciton recombination, and an increase at high temperatures when thermal ionization of excitons occurs. Our results indicate that the extent to which exciton or free-carrier recombination predominates depends on the temperature and on the strength of the built-in piezoelectric field.

Measurements in the time-domain of molecular chemiluminescence from CaCl(A2Π1/2, A2Π2/3, B2Σ+ →X2Σ+)and atomic resonance fluorescence from Ca(43P1→ 41S0) have been made in order to determine electronic branching ratios to yield CaCl(A1/2, A2/3, B) following the Cl-atom abstraction reaction of electronically excited calcium atoms, Ca[4s4p(3PJ)] , 1.888 eV above the 4s2(1S0) ground state, with CH3Cl. Ca[4s4p(3P1)] was generated by the pulsed dye-laser excitation ofground state calcium atoms at λ = 657.3 nm 21, {Ca[4s4p(n3P1)] ←Ca[4s2(1S0)]} at elevated temigeratures in the presence of CH3Cl and excess helium buffer gas in a slow flow system, kinetically equivalent to a static system. Atomic and molecular emissions were recorded following rapid Boltzmann equilibration within the Ca(43P0,1.2) spin-orbit manifold, atomic emission being restricted to the 3P1 state as the 3P0 and 3P2 states are long-lived, being so called ‘reservoir states’. Atomic fluorescence emission profiles at the resonance wavelength together with the molecular chemiluminescence emissions CaCl (A2Π1/2→X2Σ+, Δν=0, λ=621nm),CaClA2Π3/2→X2Σ+, Δν=0, λ=618nm and CaCl(B2Σ+→X2Σ+, Δν=0, λ=593nm) were recorded. The atomic and molecular emissions demonstrated exponential decays characterised by decay coefficients which were equal under identical chemical conditions thus demonstrating the production of CaCl(A2Π1/2,3/2, B2Σ+) by direct reaction of Ca(3pJ) with CH3Cl. The combination of the time-dependences of the atomic and molecular profiles as a function of the concentration of CH3Cl together with the integrated atomic and molecular intensities, placed on a common intensity scale by calibration of the optical system against a spectral radiometer, yielded branching ratios into the A2Π1/2, A2Π3/2 and B2Σ+ states of CaCl. These were found to be as follows: A1/ (2.6±1.1)2×10−3; A2/3(1.9±0.8)×10−3 and B(3.6±2.0)×10−4. To the best of our knowledge, these data represent the first measurements of electronic branching ratios of calcium chlorides into specific molecular states for reactions of Ca(3pJ) determined in the time-domain. The results are compared with various related data for total branching ratios into electronic states studied in the single collision condition for this atomic state with CH3Cl using molecular beams. These are also compared with branching ratios of SrCl(A2Π1/2, A2Π2/3, B2Σ+) following the reaction of Sr[5s5p(3pJ)]+ CH2Cl2 investigated following pulsed dye-laser excitation where the yields of SrCl(A1/2, A3/2, B)were of similar low magnitudes.

Recent advances in laser technology, with the development of extremely short-pulse, high-intensity lasers, have opened doors to new areas in atomic physics. By focusing light from an intense, short-pulse laser into a gas jet, the emission of high-order harmonics of the laser frequency has been studied. The aim of this work has been two-fold: to better understand the underlying physics of the harmonic generation process and to demonstrate the use of the generated radiation in novel applications. Experiments have been performed using both femtosecond and picosecond laser systems. The temporal coherence of harmonic radiation has been measured and characterised. We have shown that the far-field pattern of high-order harmonics separates into two spatial regions with different coherence properties. These features have been related mainly to the single-atom response, but also influenced by different phase-matching conditions. For the central region we find long coherence times, close to the expected duration of the harmonic pulse. The harmonic spectra from molecular gases have been investigated. They were found to be very similar to those obtained in rare gases, with a plateau and a cutoff whose location is strongly correlated to the ionisation potential. The conversion efficiency in the investigated molecules was not higher than that in one of the rare gases suitable for the specific wavelength region. Applications using harmonic radiation as a narrowband, coherent XUV source have been performed. Spectroscopic measurements have been made using harmonic radiation produced from a tunable laser source. Lifetimes of highly excited states in CO have been determined and the energy dependence of the photo-ionisation cross-sections of highly excited states in He has been measured. XUV interferometry using harmonic radiation has been demonstrated with femtosecond resolution, using the 11th harmonic of a femtosecond laser, to probe the spatial variation of the electron density in a plasma.

WOS:000315664200006 Atomic lifetimes and energy levels were calculated using weakest bound potential model theory for 5s(2)ns S-2(1/2) (n >= 6), 5s(2)np P-2(1/2)0 (n >= 5), 5s(2)np P-2(3/2)0 (n >= 5), 5s(2)nd D-2(3/2)0 (n >= 5), 5s(2)nd D-2(5/2)0 (n >= 5) series of the Rydberg states in neutral indium. The use of the quantum defect method and Martin's expression allowed us to supply lifetime values along by means of the series above. Some lifetimes and energy values not existing in the literature for high Rydberg states in neutral indium atom were obtained using this method. Our results nicely agree with the available experimental results and theoretical results. DOI: 10.12693/APhysPolA.123.25 University of Karamanoglu Mehmetbey Scientific Research Projects (BAP) Coordinating OfficeKaramanoglu Mehmetbey University The author gratefully acknowledges Gultekin Celik, Yasin Gokce, and Sule Ates for their help and for the support of the University of Karamanoglu Mehmetbey Scientific Research Projects (BAP) Coordinating Office.

The luminescence efficiency of SrS: Ce powders in the doping range from 0.01 to 1.0 at.% was investigated by photoluminescence decay studies. The radiative decay time of Ce3+ in SrS was determined to be 27 ns. The onset of concentration quenching at concentrations higher than about 0.7 at.% has been obtained. The photoluminescence spectrum of Ce3+ exhibits two emission bands as a consequence of the ground state splitting. The Huang–Rhys factor of the 5d-4f transition was estimated to be about 6. The inhomogeneous broadening of the emission band of samples with higher doping level has been investigated by site-selective and time-resolved spectroscopy.