Lamb shift in the metastable states of the helium atom

1966 ◽  
Vol 291 (1424) ◽  
pp. 94-105 ◽  
Keyword(s):  
Helium Atom ◽  
Lamb Shift ◽  
Metastable States ◽  
Oscillator Strengths ◽  
Triplet States ◽  
Excitation Energies ◽  
Ionization Energies ◽  
Singlet And Triplet States ◽  
Experimental Values ◽  
Average Excitation Energy

The radiative corrections of order α 3 rydbergs are evaluated for the ionization energy of the metastable states 2 1 , 3 S, of the helium atom. In the calculation of the average excitation energy k 0 , the main contribution comes from the transition to and ( ms, np ) and ( ms, ∊p ) states. The oscillator strengths for transitions to (1 s, ∊p ), (2 s, ∊p ) and (3 s, ∊p ) states are evaluated by using six-parameter wavefunction for the metastable states and a product of a hydrogenic wavefunction with Z = 2 for the s electron and a wavefunction analogous to the Hartree wavefunction for the excited p electron. Making use of these oscillator strengths and a method used by Pekeris, the values of the average excitation energies for the singlet and triplet states are found to be 77.09 ± 1.6 and 79.84 ± 1.0 rydbergs respectively. With these values of the average excitation energies, the Lamb shift corrections, including the estimate of a α 4 Ry order corrections, to the ionization energies of the singlet and triplet states become – 0.106 ± 0.018 cm -1 and –0.129 ± 0.013 cm –1 respectively. When they are added to the theoretical values of the ionization energies obtained by Pekeris, the values of the ionization energies become 32033.212 ± 0.018 an d 38454.698 ± 0.013 cm -1 compared with Herzberg’s experimental values of 32033.24 ± 0.05 an d 38454.73 ± 0.05 cm -1 for the singlet and triplet states respectively.

Protonation of the Trimethylated Pyrichrominium Ion

1986 ◽  
Vol 41 (4) ◽  
pp. 661-664
Author(s):  
J. Koput ◽  
B. Marciniak ◽  
S. Paszyc
Keyword(s):  
Transfer Reaction ◽  
Energy Levels ◽  
Proton Transfer Reaction ◽  
Oscillator Strengths ◽  
Triplet States ◽  
Excited Singlet ◽  
Triplet Energy ◽  
Charge Densities ◽  
Singlet And Triplet States ◽  
Experimental Values

pKSpectroscopic manifestations of protonation of the trimethylated pyrichrominium ion studied previously experimentally [1] are investigated using a semiempirical INDO/S Cl method. Singlet and triplet energy levels of the free ion and several protonated species are calculated, and transition energies and oscillator strengths are compared with experimental spectra. Calculated charge densities on nitrogen atoms are correlated with experimental values for the ground and lowest excited singlet and triplet states. The possibility of the proton transfer reaction (phototautomerization) in the lowest excited singlet state of monoprotonated species is discussed on the basis of INDO/S Cl calculations, fluorescence and absorption spectroscopy.

Systematic calculations of energy levels and transitions rates in Mo XXVIII

2020 ◽  
Vol 75 (8) ◽  
pp. 739-747
Author(s):  
Feng Hu ◽  
Yan Sun ◽  
Maofei Mei
Keyword(s):  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Data Sets ◽  
Electron Systems ◽  
Excitation Energies ◽  
Experimental Values ◽  
Qed Effects ◽  
Hyperfine Structures ◽  
Good Agreement

AbstractComplete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors and E1, E2, M1, and M2 line strengths, oscillator strengths, transitions rates are reported for the low-lying 41 levels of Mo XXVIII, belonging to the n = 3 states (1s22s22p6)3s23p3, 3s3p4, and 3s23p23d. High-accuracy calculations have been performed as benchmarks in the request for accurate treatments of relativity, electron correlation, and quantum electrodynamic (QED) effects in multi-valence-electron systems. Comparisons are made between the present two data sets, as well as with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology wherever available. The calculated values including core-valence correction are found to be in a good agreement with other theoretical and experimental values. The present results are accurate enough for identification and deblending of emission lines involving the n = 3 levels, and are also useful for modeling and diagnosing plasmas.

Experimental and Theoretical Studies of 2- (naphthalen-1-yl (piperidin-1-yl) methyl)phenol Compound

2020 ◽  
Vol 42 (6) ◽  
pp. 818-818
Author(s):  
Yeliz Ula Yeliz Ula
Keyword(s):  
Molecular Orbital ◽  
Theoretical Data ◽  
Biologically Active ◽  
Oscillator Strengths ◽  
Excitation Energies ◽  
Petasis Reaction ◽  
Vis Spectroscopy ◽  
Phenol Compound ◽  
Lowest Unoccupied Molecular Orbital ◽  
Experimental Values

The 2- (naphthalen-1-yl (piperidin-1-yl) methyl) phenol compound is an alkylaminophenol compound and has been experimentally synthesized by the Petasis reaction. In this study Structural analysis was carried out by FT-IR, NMR, UV-Vis spectroscopy. The high antioxidant value of the compound showed that it could be a potential biologically active drug. Theoretical data support all experimental analysis of the new compound. Comparisons were made by double method. For this purpose, DFT (B3LYP) and HF methods have been used with 6-311G ++ (d, p) set. Also, the compoundand#39;s electronic and structural properties (bond lengths, bond angles and dihedral angles), the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies, electrostatic potential (MEP), vibrational frequencies, Mulliken atomic charges, excitation energies, and oscillator strengths were calculated. As a result; the theoretical and experimental values were found to be compatible.

Highly excited 1sns states of the helium atom

1976 ◽  
Vol 54 (10) ◽  
pp. 1543-1549 ◽  
Author(s):  
Mary Kuriyan ◽  
Huw O. Pritchard
Keyword(s):  
Wave Function ◽  
Helium Atom ◽  
Lower Energy ◽  
Computer Time ◽  
Suitable Choice ◽  
Triplet States ◽  
Astrophysical Interest ◽  
Variational Calculations ◽  
Singlet And Triplet States

Variational calculations are reported on the 1sns singlet and triplet states of the helium atom, up to and including n = 26. By suitable choice of terms in the expansion for the wave function, significant economies in computer time are possible, and we quote an example of a 12-term uncorrelated wave function which gives a lower energy than Pekeris' 220-term correlated wave function. The problems of extending these calculations to much higher n (e.g. n > 100) to include states of astrophysical interest are enumerated.

Studies of C 1s → π* triplet states of carbon monoxide, benzene, ethylene, and acetylene

1994 ◽  
Vol 72 (11-12) ◽  
pp. 879-884 ◽  
Author(s):  
J. T. Francis ◽  
C. Enkvist ◽  
S. Lunell ◽  
A. P. Hitchcock
Keyword(s):  
Carbon Monoxide ◽  
Wave Functions ◽  
Oscillator Strengths ◽  
Triplet States ◽  
Triplet Splitting ◽  
Threshold Excitation ◽  
Experimental Values ◽  
First Time ◽  
Electron Energy Loss ◽  
Neglect Of Differential Overlap

The (C 1s−1,π*) triplet states of carbon monoxide, benzene, ethylene, and acetylene have been studied using electron energy loss spectroscopy with low-energy (near-threshold) excitation. The singlet–triplet splitting for the (C 1s−1,π*) states of the hydrocarbon species were measured for the first time. Intermediate neglect of differential overlap (spectroscopic) (INDO/S) calculations within the equivalent cores approximation were used to calculate (1s−1, π*) singlet–triplet splittings. The calculated values are in reasonable agreement with the experimental values for the hydrocarbon species but are significantly underestimated for CO. A strong correlation between singlet–triplet splittings and oscillator strengths for the 1s → π* transitions was noted and rationalized in terms of the dependence of both factors on the spatial overlap of 1s and π* wave functions.

The influence of solvent on the UV-visible absorption and luminescence spectra of some highly fluorescent vitamin derivatives, the products of the reaction of N-methylated vitamin Bj with cytidine (I), adenosine (II) and 2-amino-4-methylpyridine (III) is studied. Spectroscopic manifestations of protonation of I and II are also investigated using a semiempirical INDO/S CI method. Singlet and triplet energy levels of the free ion and several protonated species are calculated, and transition energies and oscillator strengths are compared with the experimental spectra. Calculated charge densities on heteroatoms in the ground and excited singlet and triplet states are correlated with changes of the experimental pKa values with excitation. The results for I and II are compared with those for the trimethylated pyrichrominium ion (III) previously studied

1990 ◽  
Vol 45 (8) ◽  
pp. 1006-1008
Author(s):  
D. Muralimohan Rao ◽  
C. Kalidas
Keyword(s):  
Energy Levels ◽  
Ion Association ◽  
Oscillator Strengths ◽  
Luminescence Spectra ◽  
Triplet States ◽  
Triplet Energy ◽  
Visible Absorption ◽  
Charge Densities ◽  
Singlet And Triplet States ◽  
Influence Of Solvent

AbstractThe conductance of HCl and HBr in water-dimethylformamide (DMF) mixtures of 10-80 wt % DMF at 25 ºC has been measured and discussed, using the three parameter conductance equation suggested by Fuoss et al. in 1965. The ionic conductances and Waiden products of the H + , C - and Br- ions have been determined and explained. No appreciable ion-association of these acids in these media has been found

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