Measurements Of Transition Probabilities Research Articles

Measurement of transition probabilities of La II using Laser Induced Breakdown Spectroscopy (LIBS)

Atomic data, such as transition probabilities of heavy elements, holds great importance in astrophysical studies. The analysis of optical and infrared IR emissions, specifically kilonovae following neutron star mergers, requires transition probabilities of the bound–bound transitions for the heavy elements involved. According to previous studies, heavy metals, particularly lanthanides such as La and Ce, contribute to the properties of the emission. However, the current databases, such as the Atomic Spectra Database at the National Institute of Standards and Technology, are incomplete, particularly for heavy elements. Therefore, we evaluate and measure the transition probabilities of lanthanide elements using laser-induced breakdown spectroscopy, which is an atomic emission spectroscopic technique based on optical emission from a laser-generated plasma. In this study, we present the transition probabilities for La II lines. The experimentally obtained transition probabilities are compared with existing data.

Research on Disability Grading Based on ICF Functional Framework: Empirical Evidence From Zhejiang Province, China.

Through assignment method, the total score of disability in multiple dimensions is obtained, and it is divided into five functional states—severe disability, partial disability, moderate disability, mild disability, and health—according to the score, and the probability of death is constructed. Using the Chinese Longitudinal Healthy Longevity Survey (CLHLS) database tracking survey data, by constructing a multistate transition probability matrix, the empirical calculation of the multistate disability transfer probability, with the help of the sixth national census data, we estimated maintenance time of each state, life expectancy, etc. The results show that the 3 year transfer probability of the initial healthy elderly is the highest, and the mortality rate is also the lowest. It can be found that the disability state transition probability measurement based on the data is more accurate than the model estimation; the disability scale and life expectancy estimated based on the multistate transition probability matrix are more reliable.

Approach to quantitative spectroscopy of atomic vapor in optical nanocells.

We present a method for recovery of narrow homogeneous spectral features out of a broad inhomogeneous overlapped profile based on second-derivative processing of the absorption spectra of alkali metal atomic vapor nanocells. The method is shown to preserve the frequency positions and amplitudes of spectral transitions, thus being applicable for quantitative spectroscopy. The proposed technique was successfully applied and tested for measurements of hyperfine splitting and atomic transition probabilities, development of an atomic frequency reference, determination of isotopic abundance, study of atom-surface interaction, and determination of magnetic-field-induced modification of atomic transition frequency and probability. The obtained experimental results are fully consistent with theoretical modeling.

Airglow Derived Measurements of Q-Branch Transition Probabilities for Several Hydroxyl Meinel Bands

Spectroscopic measurements of the hydroxyl (OH) airglow emissions are often used to infer neutral temperatures near the mesopause. Correct Einstein coefficients for the various transitions in the OH airglow are needed to calculate accurate temperatures. However, studies from some studys showed experimentally and theoretically that the most commonly used Einstein spontaneous emission transition probabilities for the Q-branch of the OH Meinel (6,2) transition are overestimated. Extending their work to several Δv = 2 and 3 transitions from v′ = 3 to 9, we have determined Einstein coefficients for the first four Q-branch rotational lines. These have been derived from high resolution, high signal to noise spectroscopic observations of the OH airglow in the night sky from the Nordic Optical Telescope. The Q-branch Einstein coefficients calculated from these spectra show that values currently tabulated in the HITRAN database overestimate many of the Q-branch transition probabilities. The implications for atmospheric temperatures derived from OH Q-branch measurements are discussed.

Measurement of atomic transition probabilities with laser-induced breakdown spectroscopy using the 3D Boltzmann plot method

This work presents a method for the determination of atomic transition probability of the emission lines of a given element using the 3D Boltzmann plot method. The method exploits the third (temporal) dimension of a classical 2D Boltzmann plot for the determination of the plasma parameters. As an example and test of the proposed method, we acquired several time-resolved spectra during laser ablation of pure tungsten sample at different energies. The time interval in which the conditions of Local Thermal Equilibrium can be guaranteed was estimated. The results lead to a criterion for the selection of preferred atomic spectral for the measurements of plasma parameters. The effect of self-absorption on the measured transition probabilities is also evaluated and discussed.

Measurements of radiative lifetimes, branching fractions, transition probabilities, and oscillator strengths for Eu II and Eu III levels

Measurements of radiative lifetimes, branching fractions, transition probabilities, and oscillator strengths for Eu II and Eu III levels

Measurement of transition probabilities between illusory melodies in ambiguous music

Measurement of transition probabilities between illusory melodies in ambiguous music

IMPROVED Cr II log(gf ) VALUES AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937.

New emission branching fraction (BF) measurements for 183 lines of the second spectrum of chromium (Cr II) and new radiative lifetime measurements from laser-induced fluorescence for 8 levels of Cr+ are reported. The goals of this study are to improve transition probability measurements in Cr II and reconcile solar and stellar Cr abundance values based on Cr I and Cr II lines. Eighteen spectra from three Fourier Transform Spectrometers supplemented with ultraviolet spectra from a high-resolution echelle spectrometer are used in the BF measurements. Radiative lifetimes from this study and earlier publications are used to convert the BFs into absolute transition probabilities. These new laboratory data are applied to determine the Cr abundance log ε in the Sun and metal-poor star HD 84937. The mean result in the Sun is 〈logε (Cr II)〉 = 5.624±0.009 compared to 〈logε(Cr I)〉 = 5.644 ± 0.006 on a scale with the hydrogen abundance log ε(H) = 12 and with the uncertainty representing only line-to-line scatter. A Saha (ionization balance) test on the photosphere of HD 84937 is also performed, yielding 〈logε(Cr II)〉 = 3.417 ± 0.006 and 〈log ε(Cr I, lower level excitation potential E. P. >30 eV)〉 = 3.3743±30.011 for this dwarf star. We find a correlation of Cr with the iron-peak element Ti, suggesting an associated nucleosynthetic production. Four iron-peak elements (Cr along with Ti, V, and Sc) appear to have a similar (or correlated) production history-other iron-peak elements appear not to be associated with Cr.

An exacting transition probability measurement - a direct test of atomic many-body theories.

A new protocol for measuring the branching fraction of hydrogenic atoms with only statistically limited uncertainty is proposed and demonstrated for the decay of the P3/2 level of the barium ion, with precision below 0.5%. Heavy hydrogenic atoms like the barium ion are test beds for fundamental physics such as atomic parity violation and they also hold the key to understanding nucleo-synthesis in stars. To draw definitive conclusion about possible physics beyond the standard model by measuring atomic parity violation in the barium ion it is necessary to measure the dipole transition probabilities of low-lying excited states with a precision better than 1%. Furthermore, enhancing our understanding of the barium puzzle in barium stars requires branching fraction data for proper modelling of nucleo-synthesis. Our measurements are the first to provide a direct test of quantum many-body calculations on the barium ion with a precision below one percent and more importantly with no known systematic uncertainties. The unique measurement protocol proposed here can be easily extended to any decay with more than two channels and hence paves the way for measuring the branching fractions of other hydrogenic atoms with no significant systematic uncertainties.

Kr ii transition probability measurements for the UV spectral region

Kr ii transition probability measurements for the UV spectral region

Ultraviolet emission lines of Si ii in cool star and solar spectra

Recent atomic physics calculations for Si II are employed within the Cloudy modelling code to analyse Hubble Space Telescope (HST) STIS ultraviolet spectra of three cool stars, Beta-Geminorum, Alpha-Centauri A and B, as well as previously published HST/GHRS observations of Alpha-Tau, plus solar quiet Sun data from the High Resolution Telescope and Spectrograph. Discrepancies found previously between theory and observation for line intensity ratios involving the 3s$^{2}$3p $^{2}$P$_{J}$--3s3p$^{2}$ $^{4}$P$_{J^{\prime}}$ intercombination multiplet of Si II at 2335 Angs are significantly reduced, as are those for ratios containing the 3s$^{2}$3p $^{2}$P$_{J}$--3s3p$^{2}$ $^{2}$D$_{J^{\prime}}$ transitions at 1816 Angs. This is primarily due to the effect of the new Si II transition probabilities. However, these atomic data are not only very different from previous calculations, but also show large disagreements with measurements, specifically those of Calamai et. al. (1993) for the intercombination lines. New measurements of transition probabilities for Si II are hence urgently required to confirm (or otherwise) the accuracy of the recently calculated values. If the new calculations are confirmed, then a long-standing discrepancy between theory and observation will have finally been resolved. However, if the older measurements are found to be correct, then the agreement between theory and observation is simply a coincidence and the existing discrepancies remain.

Method for measurement of transition probabilities by laser-induced breakdown spectroscopy based on CSigma graphs–Application to Ca II spectral lines

We propose a method for determination of transition probabilities by laser-induced breakdown spectroscopy that avoids the error due to self-absorption. The method relies on CSigma graphs, a generalization of curves of growth which allows including several lines of various elements in the same ionization state. CSigma graphs are constructed including reference lines of an emitting species with well-known transition probabilities, together with the lines of interest, both in the same ionization state. The samples are fused glass disks prepared from small concentrations of compounds. When the method is applied, the concentration of the element of interest in the sample must be controlled to avoid the failure of the homogeneous plasma model. To test the method, the transition probabilities of 9 Ca II lines arising from the 4d, 5s, 5d and 6s configurations are measured using Fe II reference lines. The data for 5 of the studied lines, mainly from the 5d and 6s configurations, had not been measured previously.

Improved and expanded measurements of transition probabilities in UV Ar ii spectral lines

Transition probabilities have a significant interest in the astrophysical field. The aim of this experiment is to extend the present data base of measured Ar II transition probabilities to the ultraviolet (UV) region and to improve the quality of some of the already existing data. Despite all the efforts made to assemble an accurate set of transition probabilities (Aki), some of the data recommended by the National Institute of Standards and Technology (NIST) for Ar II spectral lines in the UV region have uncertainties around 50percent. We measured relative intensities of spectral lines emitted from a low-pressure-pulsed discharge lamp which generates an argon plasma. Excitation temperatures of 19 000–22 000 K are determined from the Boltzmann-plot of 11 Ar II spectral lines for which accurate Aki data are available from the literature. The transition probabilities of these 11 spectral lines were used for calculating new Aki-values. Electron densities (Ne) of 3.5–9.0 × 10 22 m −3 are determined by two-wavelength interferometry method. The measurements yield to a collection of 43 atomic transition probabilities of Ar II lines in the spectral region of 294–386 nm, 11 of which are new, at least up to the authors knowledge, and 22 improved Aki-values for which the existing data in the literaturehaveuncertaintiesaround50percent.Comparisonwithprevious datashowshowour measurements have good agreement with the most accurate Aki-values from the bibliography, whereas some of the values recommended by NIST present a significant disagreement.

A LABORATORY log( gf ) MEASUREMENT OF THE Ti II 15873.84 Å H -BAND LINE IN SUPPORT OF SDSS-III APOGEE

The SDSS-III APOGEE collaboration has identified a single useable line in the H-band spectra of APOGEE target stars arising from a singly ionized species. This line of Ti II (${\lambda}_{air}$ = 15873.84 {\AA}) is therefore of great importance for use in stellar surface gravity, or log(g), determinations via the Saha equation. While a theoretical estimate of the line strength exists, to date no laboratory measurement of the line strength has been reported. Herein we report an absolute laboratory transition probability measurement for this important Ti II line. A relative line strength measurement is made of the Ti II H-band line of interest and a reference line with a previously reported absolute transition probability. This ratio is measured using multiple spectra of a high-current water-cooled HC lamp recorded with a calibrated FT-IR spectrometer.

IMPROVED Ni I log( gf ) VALUES AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937

Atomic transition probability measurements for 371 Ni I lines in the UV through near IR are reported. Branching fractions from data recorded using a Fourier transform spectrometer and a new echelle spectrograph are combined with published radiative lifetimes to determine these transition probabilities. Generally good agreement is found in comparisons to previously reported Ni I transition probability measurements. Use of the new echelle spectrograph, independent radiometric calibration methods, and independent data analysis routines enable a reduction of systematic errors and overall improvement in transition probability uncertainty over previous measurements. The new Ni I data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to derive new, more accurate Ni abundances. Lines covering a wide range of wavelength and excitation potential are used to search for non-LTE effects.

Inelastic Neutron Scattering on160Gd

The nature of low-lying excitations, Kπ=0+ bands in deformed nuclei remain enigmatic in the field, especially in relationship to quadrupole vibrations. One method of characterizing these states beyond excitation energies is through measurements of absolute transition probabilities. In the rare earth region of deformation, there are five stable Gd isotopes, 154Gd, 156Gd, and 158Gd have been studied to obtain B(E2) values, a fourth, 160Gd is the focus of this work. We have examined 160Gd with the (n, n′γ) reaction and neutron energies up to 3.0 MeV to confirm known 0+ states.

Timing Measurement Platform for Arbitrary Black-Box Circuits Based on Transition Probability

The key aspects of a good on-chip timing measurement platform are high measurement resolution, accuracy, and low area overhead. A measurement method based on transition probability (TP) has shown promising characteristics in all these areas. In this paper, the TP measurement method is examined through simulation to understand its apparent effectiveness and accuracy in measuring complex circuits. Timing uncertainties and logic glitch activities are considered in detail, and the effect of varying input vectors' probability distributions is analyzed to enable further accuracy improvements. Using a field-programmable gate array, the method is implemented and demonstrated as a modular on-chip test platform for testing complex arbitrary circuits. Practical circuits found in typical modular designs, including fixed/floating-point arithmetic and filter circuits, are chosen to evaluate the test platform. The resolution of the timing measurements ranges from 0.3 to 8.0 ps, and the measurement errors against reference measurements are found to be within 3.6%. The test platform can be applied to VLSI designs with minor area overhead, and provides designers with precise and accurate physical timing information of circuits.

IMPROVED Ti II log( gf ) VALUES AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937

Atomic transition probability measurements for 364 lines of Ti II in the UV through near IR are reported. Branching fractions from data recorded using a Fourier transform spectrometer and a new echelle spectrometer are combined with published radiative lifetimes to determine these transition probabilities. The new results are in generally good agreement with previously reported FTS measurements. Use of the new echelle spectrometer, independent radiometric calibration methods, and independent data analysis routines enables a reduction of systematic errors and overall improvement in transition probability accuracy over previous measurements. The new Ti II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to derive new, more accurate Ti abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. The Ti abundances derived using Ti II for these two stars match those derived using Ti I and support the relative Ti/Fe abundance ratio versus metallicity seen in previous studies.

IMPROVED log( gf ) VALUES FOR LINES OF Ti I AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937 (ACCURATE TRANSITION PROBABILITIES FOR Ti I)

New atomic transition probability measurements for 948 lines of Ti I are reported. Branching fractions from Fourier transform spectra and from spectra recorded using a 3 m echelle spectrometer are combined with published radiative lifetimes from laser-induced fluorescence measurements to determine these transition probabilities. Generally good agreement is found in comparisons to the NIST Atomic Spectra Database. The new Ti I data are applied to re-determine the Ti abundance in the photospheres of the Sun and metal-poor star HD 84937 using many lines covering a range of wavelength and excitation potential to explore possible non-local thermal equilibrium effects. The variation of relative Ti/Fe abundance with metallicity in metal-poor stars observed in earlier studies is supported in this study.

Rapid Assessment of Sustainable Harvesting of Leaves from the Understory Palm,Chamaedorea radicalis

We explored a rapid-assessment protocol for Chamaedorea radicalis, an understory palm from which leaves are harvested for use in the cut-greens industry. We developed a multiple-regression model relating the finite rate of population growth to vegetative and reproductive variables from a 4-year demographic study across leaf-harvesting treatments in Reserva de la Biosfera El Cielo, Tamaulipas, Mexico. The resulting model, including total fecundity of adults and mean number of leaflets, was applied to 21 populations of C. radicalis using measurements collected from a single season. Predicted estimates of population-growth rate were 0.94–1.27, but 20 of the 21 populations had predictions bracketing the net-replacement rate = 1 for population growth. We then implemented a fixed-design, life-table-response experiment to explore whether measurements of annual transition probabilities provided a superior assessment; however, addition of transition probabilities only marginally increased predictive power of the model. Therefore, implementation of this protocol is limited by imprecision of estimates of population-growth rate.Hemos explorado un método de evaluación rápida para Chamaedorea radicalis, una palma del sotobosque en el que las hojas se cosechan para su uso en la industria de follaje verde. Hemos desarrollado un modelo de regresión múltiple que relaciona la tasa finita de crecimiento de las poblaciones a las variables vegetativas y reproductivas de un estudio demográfico de 4 años a través de tratamientos de cosecha de hojas en la Reserva de la Biosfera El Cielo, México. El modelo resultante, incluyendo la fecundidad total de adultos y el número medio de foliolos, se aplicó a 21 poblaciones de C. radicalis utilizando medidas tomadas en una sola temporada. Las estimaciones previstas de la tasa de crecimiento de las poblaciones varió desde 0.94 hasta 1.27, pero en 20 de las 21 poblaciones hubo intérvalos de predicción incluyendo la tasa de sustitución neta = 1 de la tasa de crecimiento de las poblaciones. Por consiguiente implementamos un experimento de respuesta de tablas de vida de diseño-fijo para explorar si las medidas de las tasas anuales de transición proporcionan una evaluación superior; sin embargo, la adición de las tasas de transición sólo ligeramente aumentó la capacidad predictiva del modelo. Por lo tanto, la aplicación de este método es limitada por la imprecisión de las estimaciones de la tasa de crecimiento de las poblaciones.