Values Of Energy Levels Research Articles

Theoretical interpretation and new energy levels in Er II

In this work, we extend the classification of the spectrum of singly ionized erbium (Er II) both theoretically and experimentally. First, the known energy levels are interpreted parametrically using the Cowan code on two sets of configurations with interaction. Then the predictions for unknown levels are used to extend the classification of hollow cathode FT spectra of erbium recorded at the US National Solar Observatory on Kitt Peak. All 130 known levels of even parity are described with a root mean square deviation of 61 cm−1 and the summed contributions of 4f126s, 4f125d, 4f116s6p and 4f115d6p in their eigenvectors are presented. A similar agreement is obtained for 230 energy levels of odd parity. The detailed configuration percentages show that the levels of 4f126p are strongly mixed with 4f116s5d and 4f115d2. The transition probabilities obtained by means of the Cowan code are in a good qualitative agreement with the observed intensities of the classified lines and they are reported with the chains of transitions of 32 new energy levels and revised J-values for six additional levels. The energy level values and uncertainties are derived by least squares from the complete transition array of Er II with natural isotopic blending, whereas earlier compiled levels had been derived from the 168Er isotope.

Spontaneous emission in ultracold spin-polarized anisotropic Fermi seas

We examine and explain the spatial emission patterns of ultracold excited fermions in highly anisotropic trapping potentials in the presence of a spin-polarized Fermi sea of ground-state atoms. Due to the Pauli principle, the Fermi sea modifies the available phase space for the recoiling atom. This leads to the well-known modification of the atomic decay rate, but also to a spatial modulation in the probability of the emitted photon's direction. In this work we carry out the first detailed investigation into these spatial anisotropies and show that they are due to an intricate interplay between Fermi energies and degeneracy values of specific energy levels. We identify different regimes and show that the emission can be engineered to become highly directional. As the latter is usually only possible in cavity settings, our results describe an alternative idea for a directional photon source.

Impact of a Treatment Combining Nitrogen Plasma Exposure and Forming Gas Annealing on Defect Passivation of SiO<sub>2</sub>/SiC Interfaces

We propose a treatment combining nitrogen plasma exposure and forming gas annealing (FGA) to improve the electrical properties of SiO2/SiC interfaces. Although conventional FGA at 450°C alone is not effective for reducing interface traps and fixed charges, our combination treatment effectively reduces both even at moderate temperatures. We achieved further improvement by applying our treatment at higher (over 900°C) FGA temperatures, including lower interface state density (Dit) values for both deep and shallow energy levels (1 - 4 x 1011 cm-2eV-1). Considering that nitrogen incorporation promotes hydrogen passivation of interface defects, a possible mechanism for the improved electrical properties is that interface nitridation eliminates carbon clusters or Si-O-C bonds, which leads to the formation of simple Si and C dangling bonds that can be readily terminated by hydrogen. We therefore believe that our treatment is a promising method for improving the performance of SiC-based MOS devices.

Investigation of Electronic Energy Levels in InAs Quantum Dot with Shape of Lens by Using B-Spline Technique

The dependence of the electronic energy levels on the size of quantum dots (QDs) with the shape of spherical lens is studied by using the B-spline technique for the first time. Within the framework of the effective-mass theory, the values of electronic energy levels are obtained as a function of the height, radius and volume of QDs, respectively. When the height or radius of QDs increases, all the electronic energy levels lower, and the separations between the energy levels decrease. For lens-shape QDs, height is the key factor in dominating the energy levels comparing with the effect of radius, especially in dominating the ground-state level. These computational results are compared with that of other theoretical calculation ways. The B-spline technique is proved to be an effective way in calculating the electronic structure in QDs with the shape of spherical lens.

Water vapor absorption line intensities in the 1900–6600 cm −1 region

Water vapor infrared spectra have been measured using the Bruker IFS 120 HR Fourier transform spectrometer at the Physikalisch-Chemisches Institut of the Justus-Liebig-Universität Giessen. Spectra were recorded at pressure-broadening-limited resolution and at room temperature in the range of 1900–6600 cm −1. The use of fully evacuated transfer optics and a White-type multireflection cell made it possible to obtain pressure×pathlength products up to 31.27 mbar×288.5 m. These spectra have previously been used to determine experimental values of rovibrational line positions and upper energy levels of the 2 ν 2, ν 1, and ν 3 bands [Mikhailenko SN, Tyuterev VlG, Keppler KA, Winnewisser BP, Winnewisser M, Mellau G, et. al. The 2 ν 2 band of water: analysis of new FTS measurements and high- K a transitions and energy levels. J Mol Spectrosc 1997;184: 330–49] and of the 3 ν 2, ν 1+ ν 2, and ν 2+ ν 3 bands [Mikhailenko SN, Tyuterev VlG, Starikov VI, Albert KK, Winnewisser BP, Winnewisser M, et al. Water spectra in the region 4200–6250 cm −1, extended analysis of ν 1+ ν 2, ν 2+ ν 3, and 3 ν 2 bands and confirmation of highly excited states from flame spectra and from atmospheric long-path observations. J. Mol. Spectrosc. 2002; 213: 91–121]. This work presents the intensities of 3769 lines for the weak and medium transitions in the spectral range indicated. These data provide an independent source of experimental information which is complementary to intensity data available in the literature and can thus help to evaluate experimental errors and the reliability of these spectral line parameters.

Effect of Fe and Zr additions on ω phase formation in β-type Ti–Mo alloys

The effect of 1% Fe and/or 5% Zr (mass%) additions on ω phase formation was investigated for the Ti–15Mo alloy by means of X-ray diffraction analysis and hardness testing. Upon water quenching following solution treatment in the β phase region, the athermal ω phase formation could not be observed in all the alloys, regardless of Fe and Zr additions. The lattice parameter of the β phase decreases with Fe addition, while it increases with Zr addition. Solid solution strengthening by Fe and Zr is not recognized for the β phase. The isothermal ω phase formed after aging at 723 K and 773 K for 3.6 ks, which results in a decrease in the lattice parameter of the β phase and an increase in the hardness. The isothermal ω phase formation is suppressed with Fe and/or Zr additions. This is interpreted as the consequence of the increase in the average value of the bond order (Bo) for the Ti–15Mo–5Zr and Ti–15Mo–5Zr–1Fe alloys, and of the decrease in the average value of the metal d-orbital energy level (Md) for the Ti–15Mo–1Fe alloy. In addition, the degree of the suppression of isothermal ω phase can be predicted by the average values of Bo and Md.

Optimal values of rovibronic energy levels for triplet electronic states of molecular deuterium

An optimal set of 1050 rovibronic energy levels for 35 triplet electronic states of D2 has been obtained by means of a statistical analysis of all available wavenumbers of triplet–triplet rovibronic transitions studied in emission, absorption, laser and anticrossing spectroscopic experiments of various authors. We used a new method of analysis (Lavrov and Ryazanov 2005 JETP Lett. 81 371–4), which does not need any a priori assumptions concerning the molecular structure, being based on only two fundamental principles: Rydberg–Ritz and maximum likelihood. The method provides the opportunity to obtain the root-mean-square estimates for uncertainties of the experimental wavenumbers independent from those presented in the original papers. A total of 234 from 3822 published wavenumber values were found to be spurious, while the remaining set of the data may be divided into 20 subsets (samples) of uniformly precise data having close to normal distributions of random errors within the samples. New experimental wavenumber values of 125 questionable lines were obtained in the present work. Optimal values of the rovibronic levels were obtained from the experimental data set consisting of 3713 wavenumber values (3588 old and 125 new). The unknown shift between levels of ortho- and para-deuterium was found by least-squares analysis of the a3Σ+g, v = 0, N = 0 ÷ 18 rovibronic levels with odd and even values of N. All the energy levels were obtained relative to the lowest vibro-rotational level (v = 0, N = 0) of the a3Σ+g electronic state, and presented in tabular form together with the standard deviations of the empirical determination. New energy-level values differ significantly from those available in the literature.

Laboratory synthesis of industrial noise environments with predetermined statistical properties

High‐level nonGaussion noise is commonly found in a variety of industrial environments. Recent experiments have shown that for a given energy level, the statistical properties of a noise can have a strong effect on the extent of hearing loss produced in exposed individuals. In order to study, in an animal model, the effects on hearing of such noise environments, the statistical properties of the noise as embodied in the kurtosis metric must be under experimental control. For a fixed value of kurtosis and energy level the following four variables will have a strong effect on hearing loss: (1) peak histogram; (2) interval histogram; (3) duration of noise transients; and (4) level of any background Gaussian noise. Simulations have shown that the relations among kurtosis and these variables are nonlinear. However, under certain restricted conditions, these relations may be linear. Accordingly, two strategies for designing controlled industrial noise exposures are presented: (1) the interval‐priority model and (2) the duration‐priority model. Computer simulations and measurements of actual acoustic environments showed that these two models could be effectively used to simulate a wide variety of realistic industrial noises.

Predicting who will benefit from an Expert Patients Programme self-management course.

In England, the Expert Patients Programme, a lay-led chronic disease self-management course, was developed to improve self-care support and skills. The course is designed for anyone with a self-defined long-term condition, and attracts a heterogeneous group of patients. A randomised controlled trial has demonstrated effectiveness in improving subjective health. However, it is not known whether particular patient characteristics predict the impact of the course. To determine whether baseline characteristics predict clinical outcomes from attendance at a chronic disease self-management course; and to assess whether identification of such characteristics assists in targeting the course to individuals most likely to benefit. A post-hoc subgroup analysis of data from a randomised controlled trial to explore predictors of three trial outcomes: self-efficacy, energy, and health-related quality of life. Participants with self-defined long-term conditions (n = 629) were recruited from community settings in all 28 strategic health authorities in England. Multiple regression was used to examine interactions between baseline variables and trial outcomes. The predictors demonstrating significant interactions were: age and general health, and baseline values for self-efficacy, energy levels, and health-related quality of life. Participants with lower self-efficacy and health-related quality of life at baseline demonstrated more positive health outcomes. The Expert Patients Programme may have a protective effect on health-related quality of life for patients with poor health and low confidence. Younger people benefited substantially more than older people. Results suggest that positive outcomes associated with the course will be demonstrated with a wide variety of patients, although it may be worthwhile encouraging attendance of younger patients, those lacking confidence, and those coping poorly with their condition.

铊原子能级与辐射寿命的理论计算

Considering the perturbation, the results of theoretical calculation of five Rydberg series energy levels 6s^2ns^2S_1/2(n=7-20),6s^2nd^2D_3/2(n=6-20),6s^2nd^2D_5/2(n=6-20),6s^2np^2P^(0)_(1/2)(n=7-20), and 6s^2np^2P^(0)_(3/2)(n=7-20) for Tl I are presented using the weakest bound electron potential model (WBEPM) theory. Furthermore, the radiative lifetimes of this five series are also calculated. The calculated values of energy levels and lifetimes are in good agreement with the experimental results.

Hopping Transport of Electrons in Dye-Sensitized Solar Cells

A calculation of the chemical diffusion coefficient of electrons, Dn, in dye-sensitized solar cells, is presented, in the framework of the hopping model, where electron transport occurs by direct transitions between localized states in an exponential distribution. The Fermi-level dependence of Dn in the transport energy approximation is exactly the same as that in the multiple trapping model, but there are differences concerning the meaning of the parameters governing electron transport and the values of relevant energy levels inferred from experiments. The hopping model appears to describe well the experimental data of Dn from high-efficiency dye solar cells at various temperatures.

Electron-impact excitations of the autoionizing states of bismuth

Electron-impact excitation from the ground state of bismuth has been studied with electron energy-loss spectra. We have identified 14 autoionized states in the region up to 13.5 eV. Three states at 7.34, 9.97 and 11.2 eV have been recorded for the first time, they have not been observed previously either in photoabsorption spectroscopy or in arc spectra. The present energy level values are compared with the limited number of available data.

First principle study of the native defects in hexagonal aluminum nitride

The change of atom configuration in hexagonal AlN, caused by native point defects (N and Al vacancies, N and Al antisites, N and Al interstitials), are calculated firstly by plan-wave pseudopotential method with the generalized gradient approximation in the frame of density functional theory, and the most stable structure are obtained. Then the formation energy of each kind of native point defect is calculated, by which the possibilities of the six kinds of native defects to be formed during crystal growth are analyzed. Finally, the defect energy levels responding to every kind of native point defect and their electron occupancy are analyzed from the aspect of density of states. The results show that all the native defects form very deep energy levels in the band gap except N vacancy, and foreign impurities are needed to realize n- or p-type AlN. The values of defect energy levels obtained will be helpful in ascertaining the luminescence mechanism of some AlN non-band-edge emissions.

Spectral analysis of the 4d 96s configuration in eight times ionized xenon, Xe IX

A capillary light source was used to observe the spectrum of eight times ionized xenon, Xe IX, in the vacuum ultraviolet range, 270–2000 Å. Sixteen transitions have been identified as combinations between energy levels of the 4d 96s with 4d 95p configuration, and all 4d 96s levels have been determined. The present analysis is based on an accurate extrapolation of energy parameters and experimental energy level values in the Pd I isoelectronic sequence. The energy parameters were obtained with Hartree–Fock relativistic calculations. Least-squares parametric calculation has been carried out to study the fit between experimental and theoretical values.

Determination of electronic energy levels for the heteromolecular ions HeH2+, LiH3+, and BeH4+ from the Hamilton–Jacobi equation

AbstractBy making use of the Hamilton–Jacobi equation, we obtain the exact value of the electronic energy levels for the heteromolecular ions HeH2+, LiH3+, and BeH4+ as a function of nuclear distance. The Hylleraas method in association with the series established by Wind–Jaffé was applied to these molecular ions. The results are in good agreement with those found in the literature. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006

UPPER AND LOWER LIMITS ON THE EIGENVALUES OF THE SPINLESS SALPETER EQUATION

In the context of relativistic quantum mechanics, we obtain a nonlinear first order differential equation for the energy as a function of the coupling constant of a central potential. This differential equation is only exact for power law and logarithmic potentials in the massless limit. For other potentials, we discuss under which conditions the differential equation yields rigorous upper and lower limits on the value of energy levels. These results are applied to the Cornell potential used in meson spectroscopy. We also show that the method applies to noncentral potentials.

X-ray energies of circular transitions and electron screening in kaonic atoms

The QED contribution to the energies of the circular $(n,\ensuremath{\ell}=n\ensuremath{-}1)$, $2\ensuremath{\leqslant}n\ensuremath{\leqslant}13$, transitions have been calculated for several kaonic atoms throughout the periodic table, using the current world-average kaon mass. Calculations were done in the framework of the Klein-Gordon equation, with finite nuclear size, finite particle size, and all-order Uelhing vacuum polarization corrections, as well as K\"all\'en and Sabry and Wichmann and Kroll corrections. These energy level values are compared with other computed values. The circular transition energies are compared with available measured and theoretical transition energies. Electron screening is evaluated using a Dirac-Fock model for the electronic part of the wave function. The effect of electronic wave-function correlation is evaluated.

Spectrum and Energy Levels of Triply-Ionized Niobium (Nb IV)

The spectrum of triply-ionized niobium Nb IV was observed from 300 Å to 4100 Å with sliding spark discharges on 10.7-m normal- and grazing-incidence spectrographs. The existing analysis of this spectrum [Meinders, E. et al., Physica Scripta 25, 527 (1982).] was extended to include the 5s2, 5p2, 5s5d, 5s4f, 5s6s, 4d6d, 4d7s, 4d5f, 4d6f and 4d5g configurations, which are practically complete. A few levels of 4d7p and a few missing levels of the already known 4d4f configuration were also located. One level of the 4d6p configuration was revised. There are now a total of 840 lines classified as transitions between 185 energy levels. Of these, 546 lines and 107 levels are new. From the optimized energy level values, Ritz-type wavelengths with uncertainties varying from about 0.0005 Å to 0.003 Å were determined. The observed configurations were theoretically interpreted by means of Hartree-Fock calculations and least-squares fits of the energy parameters to the observed levels. The fitted parameters were used to calculate oscillator strengths for all classified lines. An improved value for the ionization energy was obtained from the 4dns(n = 4–6), 4dnf(n = 4–6), and 4d5g configurations. The adopted value is 303350 ± 180 cm-1 (37.611 ± 0.022 eV).

Revised and Extended Analysis of Eight-Times Ionized Cesium Ion: Cs IX

The ninth spectrum of cesium (Cs IX) was recorded on various spectrographs in the 100 Å–1200 Å region using a triggered spark source. The earlier analysis of Cs IX has been found to be mostly correct. The missing 4f2F levels have been found and the exact energy level values of the 5g2G and 6g2G levels have been determined. The spectrum has been considerably extended. Fifty lines are now classified in the Cs IX spectrum, 26 of them are newly classified lines. All levels of the ns (n = 5–9), np (n = 5–8), 5d, nf (n = 4–5) and ng (n = 5–9) configurations are now known. Eleven levels (J = 1/2, 3/2) of the 4d95s5p configuration and two levels 4d94f5s2P have also been established. Energy level values of 21 levels have been reported for the first time. Hartree-Fock and least-squares-fitting calculations were carried out to interpret the reported spectrum.

A few remarks on the simulation and use of crystal field energy level schemes of the rare earth ions

The usefulness of the simulation of the energy level schemes of the trivalent rare earth ( R 3+) ions in the prediction of the properties of the rare earth compounds is demonstrated for a few selected cases emphasizing the connection between different spectroscopic and magnetic properties of the R 3+ ions. The importance of the calculated energy level schemes in the UV-VUV range in interpreting complicated spectra and designing new phosphors by energy transfer and quantum cutting is described. In the absence of direct measurements, the calculated energy level values can be very useful. The possibilities to interpret the magnetic properties of the R 3+ (and R 2+) ions are described by using the wave functions of the energy levels obtained from the energy level simulations. As a fine example, it is shown how the amount of an Eu 2+ impurity can be obtained from the calculation of the paramagnetic susceptibility as a function of temperature. The problems involved in the simulation of the 7 F J crystal field energy level scheme of the Eu 3+ ion are highlighted by using a comparison between the extensive literature data and calculated level schemes.