Relative Transition Probabilities Research Articles

Electronic Structure of Neodymium(III) and Europium(III) Resolved in Solution Using High-Resolution Optical Spectroscopy and Population Analysis.

Solution chemistry of the lanthanide(III) ions is unexplored and relevant: extraction and recycling processes exclusively operate in solution, MRI is a solution-phase method, and bioassays are done in solution. However, the molecular structure of the lanthanide(III) ions in solution is poorly described, especially for the near-IR (NIR)-emitting lanthanides, as these are difficult to investigate using optical tools, which has limited the availability of experimental data. Here we report a custom-built spectrometer dedicated to investigation of lanthanide(III) luminescence in the NIR region. Absorption, luminescence excitation, and luminescence spectra of five complexes of europium(III) and neodymium(III) were acquired. The obtained spectra display high spectral resolution and high signal-to-noise ratios. Using the high-quality data, a method for determining the electronic structure for the thermal ground states and emitting states is proposed. It combines Boltzmann distributions with population analysis and uses the experimentally determined relative transition probabilities from both excitation and emission data. The method was tested on the five europium(III) complexes and was used to resolve the electronic structures of the ground state and the emitting state of neodymium(III) in five different solution complexes. This is the first step toward correlating optical spectra with chemical structure in solution for NIR-emitting lanthanide complexes.

Randentropy: A Software to Measure Inequality in Random Systems

The software Randentropy is designed to estimate inequality in a random system where several individuals interact moving among many communities and producing dependent random quantities of an attribute. The overall inequality is assessed by computing the Random Theil’s Entropy. Firstly, the software estimates a piecewise homogeneous Markov chain by identifying the change-points and the relative transition probability matrices. Secondly, it estimates the multivariate distribution function of the attribute using a copula function approach and finally, through a Monte Carlo algorithm, evaluates the expected value of the Random Theil’s Entropy. Possible applications are discussed as related to the fields of finance and human mobility.

L-shell ionization of Cd: Structure of the x-ray emission spectrum

The cadmium L x-ray spectrum induced by electron impact was analyzed in detail. The measurements were performed on a bulk pure sample using a commercial wavelength dispersive spectrometer, and the spectrum was processed with a parameter optimization method previously developed. This procedure permitted the determination of characteristic energies, relative transition probabilities and natural linewidths for this element. The results obtained here were compared to the data found in the literature, when available. Spectral structures related to satellite and radiative Auger Effect emissions were also analyzed, assessing energy shifts and relative intensities. Some of these parameters were determined for the first time, even in overlapping peaks and weak transitions, which was possible due to the robustness of the spectral processing method used.

Site use and connectivity of female grey seals (Halichoerus grypus) around Wales

Grey seals (Halichoerus grypus) are a qualifying feature of three special areas of conservation (SACs) in Wales, yet relatively little is known of their site use along this coastline. Since 1992, many individuals and organisations have contributed to a grey seal photographic identification database held by Natural Resources Wales, which is one of the largest and oldest of its kind, providing key information from grey seal haul-out sites around the Celtic and Irish Seas. Here, we investigated spatial connectivity of haul-out sites and fidelity of adult females to breeding sites. The minimum number of adult female grey seals using the area between 1992 and 2016 was 2688. Individual capture histories and relative spatial transition probabilities (Pij) between pairs of location groups were calculated. Adjacent locations were highly connected (e.g. Lleyn Peninsula and Bardsey, Pij = 0.7) but connections spanned the entire region, up to 230 km apart (e.g. Skomer and Dee Estuary, Pij = 0.004). Resights were recorded within SACs (e.g. Lleyn Peninsula and Bardsey [Lleyn Peninsula and the Sarnau SAC], Pij = 0.7), between SACs (e.g. Bardsey and Skomer [Pembrokeshire Marine], Pij = 0.03), between SACs and non-designated areas (e.g. Skerries and Bardsey, Pij = 0.09) and between sites outside any protected area (e.g. Dee Estuary and Anglesey, Pij = 0.5). While inter-annual fidelity to breeding sites was high (Pij = 0.82–1), individual female grey seals moved throughout the region. This evidence of extensive site use beyond protected areas is important for the management and conservation of grey seals around Wales.

A Distributed Channel Access Scheme for Vehicles in Multi-Agent V2I Systems

Due to the limited bandwidth of Roadside Units (RSUs) deployed in drive-thru networks, vehicles entering the network coverage with data requests have to contend for the access to the data service provided by RSUs. In order to maximize the vehicle utility, efficient access schemes are indispensable at the vehicles' side. This paper studies the optimal access control of vehicles in multi-agent drive-thru systems. In such networks, each vehicle, acting as an independent agent, can take an access decision that could potentially maximize the individual utility based on its own observations of the instantaneous environment states. Consequently, the decision of one vehicle will influence those of others, making environment states only partially observable at the vehicles' side and complicating the optimal access design. To tackle this coupling decision issue, we first formulate the optimization problem as a finite Markov Decision Process (MDP). Then, we propose a distributed access algorithm that combines the statistic learning method and the dynamic programming technique. With the proposed algorithm, missing vehicle states and related transition probabilities will be estimated by vehicles. The optimization problem is recursively solved by applying the dynamic programming technique. Simulation results are provided to show the significant improvement achieved by the proposed algorithm on multiple performance metrics. The convergence of the algorithm is numerically confirmed, verifying the stability of our approach.

Quantitative Health Impact Assessment Methodology for Societal Initiatives: A Scoping Review

Abstract Background Promoting health rather than treating disease is gaining popularity and promotion initiatives are increasingly situated in the societal domain. In this scoping review, the literature on quantitative health impact assessment (HIA) practice and methodology is explored in order to provide an overview of methods that have been used or proposed for estimating societal initiatives’ health outcomes. Methods Systematic searches were done in PubMed and Web of Science in order to identify relevant literature. A set of selection criteria ensured that studies held useful quantitative HIA methodology and a societal approach. Reference lists of all selected studies were then examined for other studies. After literature selection, quantifiable features of interest were recorded and general observations on the composition of the current literature were made. Results The literature selection process yielded 54 included studies, most of which focus on lifestyle-related determinants. Of different health outcome measurements, deaths (averted) was most frequently used, followed by life years and quality- and disability-adjusted life years. Equity is frequently mentioned, but not often estimated. Most studies made estimates based on simulation models, notably with Monte Carlo, Markov and system dynamics models (simulation period mean 46 years; median 50 years). Inputs for the models such as relative risks, transition probabilities and price elasticities were taken from census and register data, survey data, evidence from previous (scientific) studies and outcomes from stakeholder sessions. Conclusions HIA holds a wide range of practices with some overlap. Different methods’ strengths and weaknesses partly depend on the phenomenon of interest. Some policy types have standard approaches, but there is no one universal optimal method and therefore having a grasp of multiple methods is useful. Furthermore, estimating health effect distributions could make an important addition to HIA. Key messages Quantitative HIA can be conducted using various methodological bases and most studies use some form of simulation modelling. Different simulation methods are distinct, but do show some overlap. Quantitative HIA topics often relate to individual behaviour (micro-level proximal determinants). There is room for HIA method development for determinants with indirect connections to the individual.

Experimental determination of line energies, line widths and relative transition probabilities of the Gadolinium L x-ray emission spectrum

In this work the most intense x-ray lines of the L-emission spectrum of gadolinium with respect to line energies, natural line widths, and relative transition probabilities were investigated using monochromatized synchrotron radiation. The measurements were realized in the PTB laboratory at BESSY II by means of an in-house built von Hamos spectrometer based on up to two full-cylinder HAPG mosaic crystals. The von Hamos spectrometer is calibrated by means of elastically scattered photons from the employed synchrotron radiation beamline leading to a well-defined energy scale and an experimentally determined spectrometer response. A selective excitation of the gadolinium L subshells was carried out to ensure a robust deconvolution of neighboring emission lines of different L subshells. The experimental results are discussed in the context of existing data from common databases and published values since significant deviations, especially for the L and L emission lines, are observed. We further substantiate and discuss two satellite lines at the low-energy side of the L and L emission lines arising from the N4,5 subshell.

X-ray emission in atomic transitions to M shells of Hf, Ta, W, Pt and Au

The x-ray emission in atomic decays to M-shell of Hf, Ta, W, Pt and Au induced by electrons was studied. To this purpose, M x-ray spectra were acquired with a wavelength dispersive spectrometer, and processed by a parameter refinement method previously developed. A large set of atomic parameters corresponding to diagram transitions, such as characteristic energies, relative transition probabilities, and natural linewidths was determined. In addition, energy shifts and relative intensities of satellite emissions associated with M5N6,7 and M4N6 diagram lines, were assessed. The results obtained are compared with data from the literature, when available.

Identifying spatial correlation structure of multimodal permeability in hierarchical media with Markov chain approach

Outcrop analogs for aquifers allow measurements of permeability with relatively high-resolution and mapping sedimentary unit types. The spatial bivariate structure of permeability is defined by aquifer architecture. The architecture is often organized into a hierarchy of unit types, and associated permeability modes, across different spatial scales. The composite covariance (or semivariogram) is a linear summation of the auto- and cross-covariances (or semivariograms) of unit types defined at smaller scales, weighted by the related proportions and transition probabilities. It is well-known that an appreciable fraction of the composite variance arises from differences in mean permeability across unit types defined at smaller scales. Previous work has shown that the transition probabilities usually define the spatial bivariate correlation structure. The composite spatial bivariate statistics for permeability (covariance or semivariogram) will not be representative unless data locations allow proper definition of the transition probabilities of the units. Quantification of the stratal architecture can be used to better interpret the transition probabilities and thereby improve a model for the sample covariance and semivariogram. In this paper, we use an inverse modeling algorithm to fit the components of the hierarchical model, written as nested functions, in developing a hierarchical spatial correlation models. Specifically, the least-squares criterion along with prior information and other weighted constraints are used as the objective function for the inverse problem, which is solved by the Gauss–Newton–Levenberg–Marquardt method. The estimated covariance and transition probability models provides accurate representation of the spatial correlation structure of permeability for field-measured data from in Española Basin, New Mexico.

Relative L3 transition probabilities of titanium compounds as a function of the oxidation state using high-resolution X-ray emission spectrometry

The relative transition probabilities of the L3-fluorescence lines from different titanium oxides were determined using high-resolution X-ray emission spectrometry. A reliable deconvolution of the X-ray emission spectra, by means of both experimentally determined response functions and absorption correction, reduces the relative uncertainties of the relative transition probabilities to 10% for titanium and 15% for titanium dioxide. The relative L3 transition probability of metallic titanium amounts to 0.66 ± 0.07 for the Ll fluorescence line and 0.34 ± 0.07 for the Lα fluorescence line, respectively. Respective database values from existing literature vary up to a factor of 3, which shows that a determination of the fundamental parameters in the soft X-ray range with low uncertainties is needed in particular with respect to surface sensitive X-ray spectrometer methods. The relative L3 transition probability for titanium dioxide is slightly changed to 0.56 ± 0.08 for the Ll fluorescence line and 0.44 ± 0.08 for the group of fluorescence lines associated to the L3 transition of titanium dioxide that can be considered equivalent to the metal Lα fluorescence line.

Synthesis, optical spectroscopy and Judd–Ofelt analysis of Eu3+doped Li2BaP2O7 phosphors

A series of Li2BaP2O7: xEu3+ (x=0.1%, 1%, 3%, 5%) compound have been synthesized by the classic ceramic method. The obtained powders crystallize in the monoclinic system with C2/c space group. Excitation and emission spectra as well as luminescence decays were recorded. Five emission bands have been observed from the 5D0 excited state to the lower lying states 7F0, 7F1, 7F2, 7F3 and 7F4 at 578, 590, 615, 653 and 687nm respectively upon exciting the sample with 375nm wavelength. The Eu3+ Stark energy levels, the strength crystal field and the Calorimetric parameters of the Eu3+ ions in Li2BaP2O7 are calculated. A comparative study of the optical results obtained for the different Eu3+ concentrations was carried out by calculating the asymmetry ratio (1). The symmetry of the local environment of Eu3+ activators has been described in the frame of Judd–Ofelt (J–O) theory, using Ω2 and Ω4 intensity parameters derived from emission spectra. A comparison is made between these parameters in order to determine the type of connection between the Eu3+ activator ions and the Li2BaP2O7 host. The Judd–Ofelt parameters are used to calculate the relative transition probability, branching ratio and relative lifetime. The luminescence decay rates of 5D0 excited state is measured and the correspondent emission quantum efficiency is calculated. The effective bandwidth of the Eu3+ (∆λeff) and stimulated emission cross-section (σp) are also investigated.

Fiber optic thermometer using Cr-doped GdAlO3 broadband emission decay

Luminescence decay temperature measurements are performed from 800 to 1200 °C using a Cr-doped GdAlO3 (Cr:GdAlO3) sensor tip on a YAG single crystal fiber. As a thermographic phosphor, Cr:GdAlO3 combines the intense luminescence of transition metal dopants with the high temperature long decay times usually exhibited only by rare earth dopants. The proposed mechanism is emission by the Cr3+ dopant via the spin-allowed 4T2 → 4A2 transition supported by a reservoir state in 2E which populates (2E → ) through thermal equilibration. The relative energy levels and transition probabilities associated with the strong crystal field at the Al3+ site in the perovskite structure of GdAlO3 are favorable for suppressing thermal quenching of luminescence. Results from a single-fiber configuration sensor, based on a YAG fiber for its low background luminescence, are presented. Using a decay curve fitting procedure that accounts for background fluorescence, accuracies of better than ±5 °C are demonstrated.

On the relative transition probabilities of rare gases in the 1si–2pj region

We have measured the relative transition probabilities of the 1si–2pj transitions in rare gases using hollow cathode lamps. The emission spectra of each rare gas were recorded as a function of discharge current. Two independent calibration modes for the spectrometer have been used to increase the reliability of our data. Uncertainty in the data have been measured and found to be within ~5%. The relative transition probabilities are reported for 30 lines of Ne I, 25 lines of Ar I, fourteen lines of Kr I, and eighteen lines of Xe I. The present results are in good agreement with the published data. The data can also be used to calibrate the relative detection efficiency of a spectrometer over a range of 400–1000nm.

Two-photon decay of inner-shell vacancies in heavy atoms

Based on the second-order perturbation theory, we investigate the two-photon decay of $K$-shell vacancies in heavy atoms. The many-electron transition amplitude that occurs in the theory is evaluated by means of the independent particle approximation (IPA). By using this approach, computations are performed for the decay of neutral gold and are directly compared with recent experimental data, not relying on any scaling assumptions. The obtained results confirm previously identified discrepancies between the IPA theory and the experiment for the $2s\ensuremath{\rightarrow}1s$ transition, and an apparent ``resonance'' region of the $3s\ensuremath{\rightarrow}1s$ transition, but they show a moderate agreement with the measured data for the $3d\ensuremath{\rightarrow}1s$ and $4s+4d\ensuremath{\rightarrow}1s$ cases. Moreover, with the help of the IPA we discuss the validity of the nonrelativistic scaling that was employed in the past to estimate the relative two-photon transition probabilities $P$ in heavy atoms based on calculations done for lighter elements and different decay geometries. We find, in particular, that the electric-dipole angular distribution of emitted photons holds rather well even in the high-$Z$ domain, while the assumption that the relative probability $P$ is independent of nuclear charge may result in 10--30% inaccuracy of theoretical predictions.

Stark spectra of Rydberg states in atomic cesium in the vicinity of n = 18

The Stark structures in a cesium atom around n = 18 are numerically calculated. The results show that the components of 20D states with a small azimuthal quantum number |m| shift upward a lot, and those with a large |m| shift downward a little within 1100 V/cm. All components of P states shift downward. Experimental work has been performed in ultracold atomic cesium. Atoms initially in 6P3/2 state are excited to high-n Rydberg states by a polarization light perpendicular to the field, and Stark spectra with |m| = 1/2, 3/2, 5/2 are simultaneously observed with a large linewidth for the first time. The observed spectra are analyzed in detail. The relative transition probability is calculated. The experimental results are in good agreement with our numerical computation.

Transition probability measurements for some strong and weak lines of N i

We operated a high-current wall-stabilized arc to generate a low-temperature, steady-state plasma in nitrogen, with admixtures of argon, helium, and oxygen. We measured the relative atomic transition probabilities for several strong and weak 3s-3p and 3p-3d lines of neutral nitrogen and placed them on an absolute scale with experimental lifetime data available in the literature. We obtained good agreement with recent advanced calculations and an earlier measurement for the strong transitions but encountered appreciable discrepancies for weak transitions.

A spectroscopic study of laser-induced tin–lead plasma: Transition probabilities for spectral lines of Sn I

In this paper, we present transition probabilities for 97 spectral lines of Sn I, corresponding to transitions n( n = 6,7,8)s → 5p 2, n( n = 5,6,7)d → 5p 2, 5p 3 → 5p 2, n( n = 7)p → 6s, determined by measuring the intensities of the emission lines of a Laser-induced breakdown (emission) spectrometry (LIBS). The optical emission spectroscopy from a laser-induced plasma generated by a 10 640 Å radiation, with an irradiance of 1.4 × 10 10 Wcm − 2 on an Sn–Pb alloy (an Sn content of approximately 20%), in vacuum, was recorded at 0.8 µs, and analysed between 1900 and 7000 Å. The population-level distribution and corresponding temperature were obtained using Boltzmann plots. The electron density of the plasma was determined using well-known Stark broadening parameters of spectral lines. The plasma under study had an electron temperature of 13,200 K and an electron number density of 2 × 10 16 cm − 3 . The experimental relative transition probabilities were put on an absolute scale using the branching ratio method to calculate Sn I multiplet transition probabilities from available radiative lifetime data of their upper states and plotting the Sn I emission spectrum lines on a Boltzmann plot assuming local thermodynamic equilibrium (LTE) to be valid and following Boltzmann's law. The LTE conditions and plasma homogeneity have been checked. Special attention was paid to the possible self-absorption of the different transitions. The experimental results obtained have been compared with the experimental values given by other authors.

On the quantum mechanical scattering from a potential step

The problem of finding the exact spacetime particle's propagator in the presence of a potential step (interface between different materials) is revisited. In contrast to the conventional Feynman path-integral approach, integration over all energy values of the particle's spectral density matrix (discontinuity of the energy-dependent Green's function across the real energy axis) is suggested for obtaining the exact spacetime propagator. The energy-dependent Green's functions are found in the framework of the multiple scattering theory (MST). The problem of finding the step-localized energy-dependent potentials responsible for the particle's reflection from and transmission through a potential step, which are needed for MST application, is solved. The obtained exact result for the particle's propagator is expressed in terms of integrals of elementary functions and has a significantly simpler form than that reported earlier. The obtained expressions allow easy evaluation of all limiting cases, including the case of the infinitely large potential step, as well as simple numerical visualization. The square of the absolute value of the propagator, which represents the relative transition probability density between two spacetime points, is plotted and discussed in detail for the cases of particle reflection and transmission.

Experimental transition probabilities for infrared lines of Cl I

We operated a high-current, wall-stabilized arc in a gaseous mixture containing chlorine and observed $4s\text{\ensuremath{-}}4p$, $4p\text{\ensuremath{-}}4d$, and $4p\text{\ensuremath{-}}5d$ transitions in the red and near infrared spectrum. We measured their relative transition probabilities end-on and put them on an absolute scale with a lifetime value obtained from the literature. We achieved good agreement with recent sophisticated calculations and an earlier measurement for the stronger transitions, but encountered large differences for weak transitions.

Experimental transition probabilities and J-file sum rule test for the transition array 3p–3d in neutral neon

Seventy four intensities of neutral neon lines (Ne I), belonging to transitions 3p–3d, 3p′–3d, 3p–3d′, and 3p′–3d′ (all in short denoted as 3p–3d), have been measured. The neon plasma produced in a wall-stabilized arc has been applied as the excitation source for neon atoms. From measured Ne I line intensities the respective relative transition probabilities (Aki) have been determined. The absolute scale for the Aki data has been established by normalizing them to the radiative lifetime value for the level 2s22p5(2P°1/2) 3d2[3/2]°2. The obtained transition probabilities have been compared with theoretical data and with results of previous experiments. The transition probabilities have been then converted to line strengths data and used for testing the J-file sum rule for the transition array 3p–3d. Some discrepancies between the measured data set and the results predicted by the J-file sum rule have been found.