Lifetimes Of Fine-structure Levels Research Articles

Lifetimes of fine structure levels of the Li atom for 20 < n < 31 by an extended Ritz formula

Lithium and lithium-like elements look like hydrogen atoms if their two electrons and the nucleus are considered as having a core around which a single electron is orbiting. The energy and radii expressions for hydrogen atoms can be used for lithium and lithium-like elements; an important modification is introducing an effective principal quantum number. The effective principal quantum number differs from the principal quantum number of hydrogen by the quantum defect. The quantum defect has respective values for various levels of lithium and lithium-like ions. In this study, we used extended Ritz formulas to calculate quantum defects required to calculate the energies of the ns, np, nd, and nf series up to n < 31. Using these energies, we calculated transition probabilities and then the lifetimes of the lithium levels. The lifetimes were compared with the available published data; an excellent agreement was noticed. The work also extended the available list of lifetimes to higher quantum numbers. Forty lifetimes are newly calculated and presented for the first time. A polynomial formula for each of the ns, np, nd, and nf series lifetimes has been developed that fits well the lifetime values.

Fine-structure energy levels, radiative rates and lifetimes in Fe XIII

Energy levels and radiative rates for transition among the fine-structure levels of the terms belonging to the 3s23p2, 3s3p3,3s23p3d, 3p4, 3s3p23d, 3s23d2, 3p23d2, 3p33d, 3s3p3d2, 3s23p4s, 3s23p4p, 3s23p4d, 3s23p4f and 3s3p24s configurations of Si-like Iron are calculated through the CIV3 computer code using extensive configuration-interaction (CI) wavefunctions. The important relativistic effects are included through the Breit-Pauli approximation. The energy splitting of 390 fine-structure levels, oscillator strengths and radiative rates for electric-dipole-allowed and intercombination transitions and, also the lifetimes of fine-structure levels are presented and compared with available experimental and other theoretical results.

Correlation effects on fine-structure energy levels, oscillator strengths and lifetimes in Ca VII

Energy levels, oscillator strengths, and transition probabilities for transitions among the fine-structure levels of the terms belonging to the 3s23p2, 3s3p3, 3s23p3d, 3p4, 3s23p4s, 3s23p4p, 3s23p4d, and 3s23p4f configurations of Si-like Calcium are calculated using extensive configuration-interaction (CI) wave functions obtained with the CIV3 computer code of Hibbert. The relativistic effects in intermediate coupling are incorporated by means of the Breit-Pauli Hamiltonian. The energy splitting of 70 fine-structure levels, oscillator strengths and transition probabilities for electric-dipole-allowed and intercombination transitions and, also the lifetimes of fine-structure levels are presented and compared with available experimental and other theoretical results.

Energy levels, oscillator strengths and lifetimes in Si-like Ca VII

Energy levels, oscillator strengths and transition probabilities for transitions among the fine-structure levels of the terms belonging to the 3s23p2, 3s3p3, 3s23p3d, 3p4, 3s23p4s, 3s23p4p, 3s23p4d and 3s23p4f configurations of Ca VII are calculated using extensive configuration-interaction (CI) wavefunctions obtained with the CIV3 (configuration interaction version 3) computer code of Hibbert. The relativistic effects in intermediate coupling are incorporated by means of the Breit–Pauli Hamiltonian which consists of the non-relativistic term plus the one-body mass correction, Darwin term, and spin–orbit, spin–other–orbit, and spin–spin operators. Small adjustments to the diagonal elements of the Hamiltonian matrices have been made, so that the energy splittings are as close as possible to the experimental values. The energy splitting of 70 fine-structure levels, oscillator strengths and transition probabilities for electric-dipole-allowed and intercombination transitions and, also the lifetimes of fine-structure levels are presented and compared with available experimental and other theoretical results. Our calculated fine-structure energies, including their ordering, show excellent agreement (better than 0.5%) with the available experimental results. In this calculation, we also predict new data for several levels where no other theoretical and experimental results are available.

J-dependent lifetimes of the 2s2p3p 4De and 2s2p3d 4Fo terms in the boron isoelectronic sequence

Lifetimes of fine-structure levels in 2s2p3p 4D and 2s2p3d 4Fo quartets are calculated in the boron isoelectronic sequence, for C II to F V, using a multiconfiguration Hartree-Fock approach. These quarters are known from earlier experimental and theoretical studies to have different lifetimes for different J-levels, owing to spin-induced transitions, mainly to doubler states in 2s22p and 2s2p2 configurations. Present work reproduces adequately the experimental features in F V and O IV. We also predict a weak J-dependency of the lifetimes in N III, in contrast to earlier measurements.

Lifetimes of fine structure levels of metastable H2 in the c 3Πu state

Lifetimes of fine structure levels of the v=0 level of the metastable c 3Πu state of H2 are calculated by considering both the forbidden predissociation and the forbidden radiative transition to the same dissociative b 3Σu+ state as the competing decay processes. The decay rate Wp due to forbidden predissociation is calculated for the rotational level N=1 of ortho-H2 and N=2 of para-H2. The weak spin–orbit and spin–spin interactions are the perturbative interactions to mix the metastable c 3Πu state with the repulsive b 3Σu+ state. For the fine structure levels J=N, the forbidden predissociative decay rate Wp calculated is approximately 14 times larger than the previously calculated radiative decay rate Wr. The resulting lifetimes for these J=N levels (which are 0.12 msec for N=1 and 0.11 msec for N=2) are shorter than the detection limit of Johnson’s time of flight experiment. For the fine structure levels J=N±1, Wp is approximately 1/3 of Wr (except for case J=N−1=0, where Wp=0) and the resulting lifetimes vary from 1.3 to 1.4 msec. The lifetimes of non-metastable levels which predissociate via the strong Λ-doubling (or orbit–rotation) interaction are also calculated. They are 1.36×10−9 sec for N=1 of para-H2 and 4.52×10−10 sec for N=2 of ortho-H2.