Values Of Energy Levels Research Articles

Resummation of divergent perturbation series: Application to the vibrational states of H2CO molecule.

Large-order Rayleigh-Schrödinger perturbation theory (RSPT) is applied to the calculation of anharmonic vibrational energy levels of H2CO molecule. We use the model of harmonic oscillators perturbed by anharmonic terms of potential energy. Since the perturbation series typically diverge due to strong couplings, we apply the algebraic approximation technique because of its effectiveness shown earlier by Goodson and Sergeev [J. Chem. Phys. 110, 8205 (1999); ibid. 124, 094111 (2006)] and in our previous articles [A. D. Bykov et al. Opt. Spectrosc. 114, 396 (2013); ibid. 116, 598 (2014)]. To facilitate the resummation of terms contributing to perturbed states, when resonance mixing between states is especially strong and perturbation series diverge very quick, we used repartition of the Hamiltonian by shifting the normal mode frequencies. Energy levels obtained by algebraic approximants were compared with the results of variational calculation. It was found that for low energy states (up to ∼5000 cm(-1)), algebraic approximants gave accurate values of energy levels, which were in excellent agreement with the variational method. For highly excited states, strong and multiple resonances complicate series resummation, but a suitable change of normal mode frequencies allows one to reduce the resonance mixing and to get accurate energy levels. The theoretical background of the problem of RSPT series divergence is discussed along with its numerical analysis. For these purposes, the vibrational energy is considered as a function of a complex perturbation parameter. Layout and classification of its singularities allow us to model the asymptotic behavior of the perturbation series and prove the robustness of the algorithm.

The fourth spectrum of iridium (Ir IV)

The spectrum of three times ionized iridium, Ir IV, was investigated in the 650–2045 Å wavelength region. The analysis has led to the determination of the 5d6, 5d56s and 5d56p configurations. Twenty-nine of 34 theoretically possible 5d6 levels, 44 of 74 possible 5d56s levels and 150 of 214 possible 5d56p levels have been established. The levels are based on 1348 classified spectral lines. The level structure and transition probabilities were calculated using the orthogonal operators technique. The energy parameters have been determined by the least squares fit to the observed levels. Calculated energy values and LS-compositions obtained from the fitted parameter values are given. The level optimization procedure and the determination of uncertainties of the obtained energy level values are discussed.

Syntheses and Optoelectronic Properties of Planar Compounds 3,7‐diaryl‐1,5,2,4,6,8‐dithiotetrazocine

Planar molecules 3,7‐diaryl‐1,5,2,4,6,8‐dithiotetrazocines would be potential acceptor materials of organic solar cell because of their containing SN units. One‐pot synthetic procedures of 3,7‐diaryl‐1,5,2,4,6,8‐dithiotetrazocine compounds are developed to improve their yields up to 2.1–5.9 times as much as those in literatures. The geometries of title compounds were optimized by the density functional theory calculations. Their optoelectronic properties were studied by ultraviolet and cyclic voltammetry spectra and fluorescence quenching experiments. The highest occupied and lowest unoccupied molecular orbital energy level values show that these compounds are suitable to be employed as acceptor materials for developing bulk heterojunction organic solar cells with high open circuit voltages. Emission fluorescence of poly(3‐hexylthiophene) at excited state in dichloromethane was quenched by addition of title compound. Therefore, these compounds used as acceptor materials could exhibit good mobility.

Spectral characterizations and photophysical properties of one-step synthesized blue fluorescent 4′-aryl substituted 2,2′:6′,2′′-terpyridine for OLEDs application

We have synthesized a series of 4′-aryl substituted 2,2′:6′,2′′-terpyridine (terpy) derivatives, namely 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine (C-1), 4′-(2-furyl)-2,2′:6′2′′-terpyridine (C-2), and 4′-(3,4,5-trimethoxyphenyl)-2,2′:6′,2′′-terpyridine (C-3). The synthesized terpy compounds were characterized by elemental analyses, FTIR, NMR (1H and 13C), and ESI-Mass spectrometry. Photophysical, electrochemical and thermal properties of terpy compounds were systematically studied. Maximum excitation band was observed between 240 and 330nm using UV–visible spectra, and maximum emission peaks from PL spectra were observed at 385, 405 and 440nm for C-1, C-2 and C-3 respectively. Fluorescence lifetime (τ) of the fluorophores was found to be 0.35 and 1.55ns at the excitation wavelength of 406nm for C-1 and C-2 respectively, and τ value for C-3 was found to be 0.29ns at the excitation wavelength of 468nm. We noticed that the calculated values of HOMO energy levels were increased from 5.96 (C-1) to 6.08 (C-3)eV, which confirms that C-3 derivative is more electrons donating in nature. The calculated electrochemical band gaps were 2.95, 2.82 and 3.02eV for C-1, C-2 and C-3 respectively. These blue fluorescent emitter derivatives can be used as an electron transport and electroluminescent material to design the blue fluorescent organic light emitting diode (OLED) applications.

The decay of 194Au to levels in 194Pt

High-resolution gamma-ray spectroscopy measurements of the energies and intensities of the γ rays emitted in the decay of 194Au (produced following the decay of 447-y 194Hg) have been made with increased precision relative to previous studies, leading to correspondingly improved values for β-decay branching intensities and energy levels in the daughter 194Pt. Numerous newly observed transitions are reported, and two possible new levels in 194Pt are suggested.

Spectrum and energy levels of quadruply-ionized molybdenum (Mo V)

The spectrum of quadruply-ionized molybdenum Mo V was observed from 200 to 4700 Å with sliding spark discharges on 10.7 m normal- and grazing-incidence spectrographs. The existing analyses of this spectrum (Tauheed et al 1985 Phys. Scr. 31 369; Cabeza et al 1986 Phys. Scr. 34 223) were extended to include the 5s2, 5p2, 5s5d, 5s6s, 4d5f, and 4d5g configurations as well as the missing 3H6 level of 4d4f and about 75 levels of the core-excited configuration 4p54d3. The values of the 4d5d 1S0, 5s5p 1P1, and 4d6p 3P0 levels were revised. There are now about 900 lines classified as transitions between 66 even parity and 191 odd parity energy levels. Of these, about 600 lines and 130 levels are new. From the optimized energy level values, Ritz-type wavelengths were determined for about 380 lines, with uncertainties varying from 0.0003 to 0.002 Å. 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. A few unclassified lines and undesignated levels are also given. An improved value for the ionization energy was obtained by combining the observed energy of the 4d5g configuration with an ab initio calculation of its term value. The adopted value is 438 900 ± 150 cm−1 (54.417 ± 0.019 eV).

A Novel High Precision Analytic Potential Function for Diatomic Molecules

A new analytical potential energy functions is presented, the potential energy function is examined by 13 examples of different diatomic molecules or ions——homonuclear ground-state for neutral diatomic molecules, heternuclear ground-state for charged diatomic molecular ion, heternuclear excitation-state neutral diatomic molecules ,heternuclear excited-state for charged diatomic molecular ion, homonuclear excited-state for neutral diatomic molecule , homonuclear excited-state for charged diatomic moleculeetc.. as a consequence, the theoretical values of the vibrational energy level of molecules calculated by the potential energy function are in high-precision consistent with RKR data (Rydberg-Klein-Rees) or experimental data.

A Criterion for Topological Close-Packed Phase Formation in High Entropy Alloys

The stability of topological close-packed (TCP) phases were found to be well related to the average value of the d-orbital energy level \( \overline{Md} \) for most reported high entropy alloys (HEAs). Excluding some HEAs that contain high levels of the elements aluminum and vanadium, the results of this study indicated that the TCP phases form at \( \overline{Md} \) > 1.09. This criterion, as a semi-empirical method, can play a key role in designing and preparing HEAs with high amounts of transitional elements.

Rigid한 Phenothiazine-Quinoxaline D/A 공액 고분자 구조의 용해성 향상 연구 및 유기박막태양전지로의 특성 분석

In this study, two kinds of polymer (PPQX-2hdPTZ (P1), POPQX-2hdPTZ (P2)) were synthesised by Suzuki coupling reaction based on phenothiazine derivative as electron-donor and quinoxaline derivative as electron-acceptor. Microwave synthesis workstation was used to shorten the polymerization time and increase the degree of polymerization. The physical, thermal stability, optical and electrochemical properties of the synthesized polymer were confirmed. The thermal stability of two polymers was outstanding as the initial decomposition temperature was 323-328°C. And additional substituted alkoxy chain on P2 showed higher degree of polymerization. An analysis of electrochemical properties, all polymer had similar HOMO energy level values. Device was fabricated by ITO/PEDOT:PSS/active layer/BaF2/Al structure and photovoltaic properties were confirmed. Each device has a different film thickness and the resulting change in PCE was confirmed. As a result the thinner thickness of the film showed a high efficiency (PCEmax: P1 = 1.0%, P2 = 1.1%).

The absorption spectrum of 13CH4 in the region of the 2ν3 band at 1.66 µm: Empirical line lists and temperature dependence

The absorption spectrum of 13CH4 has been recorded at 296K and 80K by differential absorption spectroscopy (DAS) in the high energy part of the tetradecad (5853–6201cm−1) dominated by the 2ν3 band near 5988cm−1. The achieved noise equivalent absorption of the spectra (αmin≈1×10−7cm−1) allowed us to double the number of 13CH4 lines previously measured in the region (our lists include about 7200 and 3700 lines at 296 and 80K, respectively). Empirical values of the lower state energy level, Eemp, were systematically derived from the intensity ratios of the lines measured at 80K and 296K. Overall 2782 Eemp values were determined extending significantly the previous set of about 1200 Eemp values available in the literature. The corresponding empirical values of the rotational quantum number, Jemp, show a clear propensity to be close to an integer, illustrating the validity of the method. The line lists at 296K and 80K, provided as Supplementary material, are discussed in relation with line lists and rovibrational assignments available in the literature.

Neutron capture cross sections of 194Hg and the decays of 195Hg

The thermal cross section and resonance integral have been determined for radiative neutron capture by radioactive 194Hg by observing the γ rays emitted in the decay of 195Hg. Captures leading to the low-spin isomer of 195Hg give σ=877b and I=10,270b, while captures leading to the high-spin isomer give σ=49b and I=608b. Energies and intensities of the γ rays emitted in the decays of 195Hg produced by neutron capture have been obtained with increased precision relative to previous studies with sources produced by other reactions, leading to correspondingly improved values for β-decay branching intensities and energy levels in 195Au. New values for the half-lives of 195gHg and 195mHg are also reported.

Helium atom in an external electric field: Exact diagonalization

An exact diagonalization method is applied to solve the quantum-mechanical problem of spinless helium atom in an external electric field of arbitrary magnitude. The basis set for two-electron problem is built from different pair combinations ψnalama(αra)ψnblbmb(αrb) of orthonormalized single-particle hydrogen-like wave functions ψnml(r) belonging to any possibly bound states of the individual a- and b-electrons in the Coulomb central field renormalized by the scale parameter α > 0. Within the selected basis the matrix elements of the total Hamiltonian allows an exact analytical representation in the form of finite numerical sums. The diagonalization procedure is performed by Jacobi algorithm for N × N square Hermitian matrix built on the basis of dimension N = 25. The systematics and the numerical values of the low-lying energy levels at zero field are in good agreement with known experimental data. The field dependences of low-lying levels (Stark effect) and polarizability in the ground state of helium a...

Theoretical investigation of the open circuit voltage: P3HT/9,9'-bisfluorenylidene derivative devices.

The calculation of the power conversion efficiency (PCE) value for a bulk heterojunction (BHJ) organic solar cell is complex due to the wide number of parameters involved in the processes. This study focuses the attention on the molecular parameters involved into the open circuit voltage and the PCE definitions and in particular on the electronic coupling and on the lowest unoccupied molecular orbital (LUMO) of the acceptor. A simplified model system composed by a polymer as donor and a novel class of molecules (9,9'-bisfluorenylidene derivatives) as acceptor has been proposed as prototype to simulate the BHJ organic solar cell interface. Several substituents on different positions are tested and the chemical nature/position of substituents have a relevant influence on the electronic coupling and energy level values. Geometrical and electronic properties are obtained using density functional theory (DFT) and time-dependent (TD)-DFT calculations, respectively. A new hypothesis suggests that the minimization of the electronic coupling between the LUMO of the acceptor and the highest occupied molecular orbital (HOMO) of the donor can enhance the PCE reducing the recombination interface processes and calculations showing the possibility to minimize this parameter and fine-tune acceptor energy level through the acceptor functionalization. An accurate balance between electronic coupling and on the LUMO of the acceptor allows to propose the more performing candidate as electron acceptor in a P3HT/99'BF derivative BHJ solar cell.

The Synthesis of Air Filters from Silk Cocoons Coated TiO<sub>2</sub> for Use in Air Purifier

The purpose of this research was to synthesize and form fibroin silk air filter (SF filter) coated and non-coated with titanium dioxide. For use in indoor air pollution treatment. The main air pollutant to be treated is PM2.5. However, VOC removal also investigaed in this study. The synthesis involved degumming process using 0.5 wt % Na2CO3 at 90°C for 60 minutes. Titanium dioxide (TiO2) used in the study was a catalyst Tipaque brand (code A-220 (Anatase)). Results from studying on physical property by scanning electron microscope found that silk fibre was an ununiformly arrangement structure. SF filter coated with TiO2 showed that TiO2 distributed uniformly on the filter. The silk fibroin filters were brought to analyze for the energy band gap in order to find the energy value that the catalyst was needed to stimuate reaction in the photocatalytic process. It was found that TiO2 1-7.5 %(w/v) catalyst coated on the silk fibroin filters had the highest value of light absorption at 390 nanometers, which agreed with the value of energy level in the band gap period of 3.18 eV.The results from efficiency studies of SF filters in the treatment of indoor air pollution (generated from incense fume of 0-2 micron in size) indicated that the best treatment efficiency was 99.76%. In which SF filter non-coated with TiO2 was used, and initial PM2.5 concentration was 5 mg/m3, air flow rate was 3.93 m3/min. Treatment period was 8 hours.

Rethinking Band Bending at the P3HT–TiO2 Interface

The advancement of solar cell technology necessitates a detailed understanding of material heterojunctions and their interfacial properties. In hybrid bulk heterojunction solar cells (HBHJs), light-absorbing conjugated polymers are often interfaced with films of nanostructured TiO2 as a cheaper alternative to conventional inorganic solar cells. The mechanism of photovoltaic action requires photoelectrons in the polymer to transfer into the TiO2, and therefore, polymers are designed with lowest unoccupied molecular orbital (LUMO) levels higher in energy than the conduction band of TiO2 for thermodynamically favorable electron transfer. Currently, the energy level values used to guide solar cell design are referenced from the separated materials, neglecting the fact that upon heterojunction formation material energetics are altered. With spectroelectrochemistry, we discovered that spontaneous charge transfer occurs upon heterojunction formation between poly(3-hexylthiophene) (P3HT) and nanocrystalline TiO2. It was determined that deep trap states (0.5 eV below the conduction band of TiO2) accept electrons from P3HT and form hole polarons in the polymer. This equilibrium charge separation alters energetics through the formation of interfacial dipoles and results in band bending that inhibits desired photoelectron injection into TiO2, limiting HBHJ solar cell performance. X-ray photoelectron spectroscopic studies quantified the resultant vacuum level offset to be 0.8 eV. Further spectroelectrochemical studies indicate that 0.1 eV of this offset occurs in TiO2, whereas the balance occurs in P3HT. New guidelines for improved photocurrent are proposed by tuning the energetics of the heterojunction to reverse the direction of the interfacial dipole, enhancing photoelectron injection.

Hydrogen atom in a strong magnetic field

We study the energy spectrum of atomic hydrogen in strong and ultra-strong magnetic fields, in which the hydrogen electron starts to move relativistically and quantum electrodynamics effects become important. Within the adiabatic approximation, highly accurate energy level values are obtained analytically for , which are then compared with asymptotic and numerical results available in the literature. A characteristic feature noted in electron motion in a strong magnetic field is that for , the transverse motion becomes relativistic, while the longitudinal motion (along ) can be described by nonrelativistic theory and is amenable to the adiabatic approximation. Topics discussed include: the qualitative difference in the way odd and even levels change with the magnetic field (for ); the removal of degeneracy between odd and even atomic states; spectral scaling relations for different quantum numbers and different field strengths; the shape, size, and quadrupole moment of the atom for ; radiative transitions in a strong magnetic field; relativistic QED effects, including the effects of vacuum polarization and of the electron anomalous magnetic moment on the energy level positions; Coulomb potential screening and energy level freezing at ; and the possibility of the Zeldovich effect in the hydrogen spectrum in a strong magnetic field. The critical nuclear charge problem is briefly discussed. Simple asymptotic formulas for , valid for low-lying levels, are proposed. Some of the available information on extreme magnetic fields produced in the laboratory and occurring in space is given. The Coulomb renormalization of the scattering length is considered in the resonance situation with a shallow level in the spectrum.

Progress in the analysis of the even parity configurations of tantalum atom

The experimental work of L. Windholz, G.H. Guthohrlein and co-workers, concerning observation of the tantalum spectrum, yield many information about new energy levels and hyperfine structure splitting. We contribute the results of the complex parametric studies of the fine- and hyperfine structure of the mentioned element up to second-order of perturbation theory, including the effects of closed shell - open shell excitations. The work has been performed for the systems including 47 even configurations. The values of the radial parameters describing the one- and many-body interactions effects on atomic structure are given. We predicted values of energy levels and their A- and B- hyperfine structure constants, also for experimentally levels not observed up to now.

Electrochemical Study on Rhodamine 6G-Indole Based Dye for HOMO and LUMO Energy Levels

The energy levels are very important to investigate properties of organic dye materials. These values of energy levels can be calculated and compared with absorption spectra, cyclic voltammetric measurement and computer simulative calculation. In this study, absorption and emission changes were observed by complexation between rhodamine 6G based dye and mercury. This is related to spirolactam ring system of rhodamine 6G based dye. According to structural change of this dye, HOMO and LUMO energy levels were investigated and determined by their values with different approaches.

Electrochemical Charging of CdSe Quantum Dot Films: Dependence on Void Size and Counterion Proximity

Films of colloidal quantum dots (QDs) show great promise for application in optoelectronic devices. Great advances have been made in recent years in designing efficient QD solar cells and LEDs. A very important aspect in the design of devices based on QD films is the knowledge of their absolute energy levels. Unfortunately, reported energy levels vary markedly depending on the employed measurement technique and the environment of the sample. In this report, we determine absolute energy levels of QD films by electrochemical charge injection. The concomitant change in optical absorption of the film allows quantification of the number of charges in quantum-confined levels and thereby their energetic position. We show here that the size of voids in the QD films (i.e., the space between the quantum dots) determines the amount of charges that may be injected into the films. This effect is attributed to size exclusion of countercharges from the electrolyte solution. Further, the energy of the QD levels depends on subtle changes in the QD film and the supporting electrolyte: the size of the cation and the QD ligand length. These nontrivial effects can be explained by the proximity of the cation to the QD surface and a concomitant lowering of the electrochemical potential. Our findings help explain the wide range of reported values for QD energy levels and redefine the limit of applicability of electrochemical measurements on QD films. Finally, the finding that the energy of QD levels depends on ligand length and counterion size may be exploited in optimized designs of QD sensitized solar cells.

Comparison of Bond Order, Metal d Orbital Energy Level, Mechanical and Shape Memory Properties of Ti–Cr–Sn and Ti–Ag–Sn Alloys

Bond order (B0) and metal d orbital energy level (Md) values were calculated for our recently developed Ti­(6,7)Cr­3Sn and Cr substituted Ti­(6,7)Ag­3Sn alloys developed in this study. Position of these alloys in the B0-Md phase stability map developed by Morinaga and co-workers was then determined. Phase constitution, mechanical and shape memory properties were co-related with the position of Ti­(6,7)Cr­3Sn and Cr substituted Ti­(6,7)Ag­3Sn alloy in the B0-Md phase stability map. Cr substitution with Ag has resulted drastic decrease in the bond order (B0) and metal d orbital energy level (Md) values, resulting drastic decrease in the strength, fracture strain and shape memory properties. Position of Ti­(6,7)Cr­3Sn alloys was within the twinning region of B0-Md phase stability map and these alloys exhibited good mechanical and shape memory properties due to stress induced martensitic transformation. It is concluded that position of developed Ti­Cr­Sn and Ti­Ag­Sn alloys in the B0-Md phase stability map not only affect the phase constitution but also the mechanical and shape memory properties.