Energy levels for the stable isotopes of atomic helium(4He I and 3He I)

2006 ◽  
Vol 84 (2) ◽  
pp. 83-105 ◽  
Author(s):  
Donald C Morton ◽  
Qixue Wu ◽  
G WF Drake
Keyword(s):  
Stable Isotopes ◽  
Ab Initio ◽  
Ionization Potential ◽  
Energy Levels ◽  
Laboratory Data ◽  
Ionization Energies ◽  
Isotope Shifts ◽  
Magnetic Perturbations ◽  
Atomic Helium

We calculate very accurate ab initio ionization energies for both 4He I and 3He I as well as the isotope shifts for n = 1 to 10, L = 0 to 7 and combined these with precise laboratory data to produce a new table of levels for 4He I and the first table for 3He I. We adopted an experimental ionization potential of 5945 204 290 ± 33 MHz for 4He I and derived 5944 890 770 ± 33 MHz for 3He I. Additional calculations of the magnetic perturbations of 3He I provide the hyperfine levels, which compare favourably with the available measurements.PACS Nos.: 31.30.Gs, 31.30.Jv

scholarly journals Molecular Data for Stellar Opacities

1995 ◽  
Vol 10 ◽  
pp. 576-578
Author(s):  
Uffe Gråe Jørgensen
Keyword(s):  
Ab Initio ◽  
Energy Levels ◽  
Laboratory Data ◽  
Molecular Data ◽  
Molecular Ions ◽  
Molecular Constants ◽  
Excitation Energies ◽  
Line Intensities ◽  
Lower Accuracy ◽  
Ab Initio Computations

In total, 40 neutral diatomic molecules, 2 molecular ions, and 7 polyatomic molecules are known from observed photospheric stellar spectra. Line data for opacity computations (i.e., lists of line frequencies, intensities, and excitation energies) exist for 17 of these molecules, although the data are complete only for a handful of them. A detailed description of stellar photospheric molecules can be found in Tsuji (1986), and the existing opacity data have been reviewed by Jorgensen (1995).Listed line frequencies in the data bases are either the measured values, or based on computed molecular constants obtained from fits to measured values. Attempts to compute ab initio line frequencies have so far resulted in lower accuracy than what is obtained by use of molecular constants. Published line strengths include measured values as well as ab initio values. For strong bands the ab initio intensities are as accurate as the laboratory values, whereas measured values for weak bands are generally more accurate than the ab initio values. The primary advantage of ab initio computations is therefore that the complete set of all transitions can be obtained. Exploratory studies have shown that completeness of the line data is crucial for the obtained stellar photospheric structure.As an alternative to the ab initio computations of the line intensities, fits to experimental data have been attempted. The most promising method seems to be to fit the dipole function by use of a Padé approximant. Combined with a potential fitted to experimental energy levels, such a dipole function can in principle be used to predict the complete list of band intensities and line intensities for all bands with energies up to the molecular dissociation energy. The part of the dipole function which corresponds to the largest stretching (or bending) of the molecule is the most uncertain in such fits as well as in ab initio computations. This part is responsible for most of the many weak transitions, and large uncertainties are therefore to be excepted in the computed intensities of the weak spectral bands. As these are of major importance for the stellar photospheric structure (due to their huge number and their pseudo continuous appearance in the spectrum), a particularly large effort is desirable in comparing computed intensities with laboratory data for a representative sample of weak bands. Unfortunately, only few measurements of weak bands exist.

Ab initio study of the isomerization HNC → HCN. I. Ab initio calculation of the HNC ⇌ HCN potential surface and the corresponding energy levels

1983 ◽  
Vol 82 (3) ◽  
pp. 317-336 ◽  
Author(s):  
Miljenko Perić ◽  
Mirjana Mladenović ◽  
Sigrid D. Peyerimhoff ◽  
Robert J. Buenker
Keyword(s):  
Ab Initio ◽  
Ab Initio Calculation ◽  
Potential Surface ◽  
Energy Levels ◽  
Ab Initio Study

scholarly journals X-ray laser lines in nickel-like erbium

2016 ◽  
Vol 94 (8) ◽  
pp. 705-711
Author(s):  
Wessameldin S. Abdelaziz
Keyword(s):  
Ionization Potential ◽  
Excited States ◽  
Ground State ◽  
Energy Levels ◽  
Single Electron ◽  
Electron Densities ◽  
X Ray ◽  
Electron Excited States

Energy levels of 249 excited levels in nickel-like erbium are calculated using the 3s23p63d10 as a ground state and the single electron excited states from n = 3 to n = 4, 5 orbitals, calculations have been performed using FAC code (Gu. Astrophys. J. 582, 1241 (2003). doi:10.1086/344745 ). The populations are calculated over electron densities from 1020 to 1023 cm−3 and electron temperatures 1/2, 3/4 of the ionization potential of Ni-like Er. The gain coefficients of the transitions are calculated.

Ab initio Study on Ionization Energies of 3-Amino-1-propanol

2011 ◽  
Vol 24 (3) ◽  
pp. 315-318 ◽  
Author(s):  
Ke-dong Wang ◽  
Ying-bin Jia ◽  
Zhen-jiang Lai ◽  
Yu-fang Liu
Keyword(s):  
Ab Initio ◽  
Ab Initio Study ◽  
Ionization Energies

scholarly journals The high-energy band in the photoelectron spectrum of alkanes and its dependence on molecular structure

1999 ◽  
Vol 64 (11) ◽  
pp. 673-680 ◽  
Author(s):  
Ivan Gutman ◽  
Viktorija Gineityte ◽  
Mirko Lepovic ◽  
Miroslav Petrovic
Keyword(s):  
Molecular Structure ◽  
Energy Band ◽  
Photoelectron Spectrum ◽  
Line Graph ◽  
Energy Levels ◽  
Molecular Graph ◽  
High Energy ◽  
Saturated Hydrocarbons ◽  
Ionization Energies ◽  
Laplacian Eigenvalues

In the model for the ionization energies of the C2s-electrons in saturated hydrocarbons, put forward by Heilbronner et al., the energy levels are calculated as eigenvalues of the line graph of the hydrogen-filled molecular graph. It is now shown that in the case of alkanes, these energy levels are related to the Laplacian eigenvalues of the molecular graph. A few rules are formulated, relating these ionization energies with molecular structure.

A study of the vacuum pyrolysis of 1,2,3-benzotriazines. The Hel ultraviolet photoelectron spectra of benzazete and o-benzyne

1995 ◽  
Vol 73 (1) ◽  
pp. 146-149 ◽  
Author(s):  
Nick Henry Werstiuk ◽  
Chandra Deo Roy ◽  
Jiangong Ma
Keyword(s):  
Heat Source ◽  
Ab Initio ◽  
Photoelectron Spectra ◽  
Equilibrium Geometry ◽  
Ionization Energies ◽  
Vacuum Pyrolysis ◽  
Ab Initio Hf

A CW CO2 laser is used as a directed heat source to carry out the vacuum pyrolysis of 1,2,3-benzo-triazine (1a) and 4-methyl-1,2,3-benzotriazine (1b). We report the first HeI photoelectron (pe) spectrum of benzazete (2a), which correlates with ionization energies calculated with HAM/3 using an equilibrium geometry obtained at the ab initio HF/6-31G** level of the theory. The pe spectrum of o-benzyne (3) obtained in this study correlates with the spectrum published by Zhang and Chen, but not with the spectra reported in two earlier publications. Keywords: 1,2,3-benzotriazines, vacuum pyrolysis, HeI ultraviolet photoelectron spectra, benzazete, benzyne.

Theory of DX Centers in AlxGa1-x Alloys

1989 ◽  
Vol 163 ◽  
Author(s):  
D. J. Chadi ◽  
S. B. Zhang
Keyword(s):  
Theoretical Model ◽  
Ab Initio ◽  
Electronic Properties ◽  
Lattice Distortion ◽  
Substitutional Site ◽  
Ionization Energies ◽  
Dx Centers ◽  
Large Lattice ◽  
Self Consistent ◽  
Pseudo Potential

AbstractA theoretical model for DX centers which explains their unusual electronic properties in terms of two distinct bonding configurations for donor impurities in AlxGa1-x As alloys is examined. The results of our ab initio self-consistent pseudo-potential calculations show that for x > ≃20%, the normal fourfold coordinated substitutional site becomes unstable with respect to a large lattice distortion. The model explains the large difference between the thermal and optical ionization energies of DX centers.

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