Transitions In Multiply Charged Ions Research Articles

One and two electron transitions in multiply charged ions and helium collisions

In this paper, an extension of the already-developed and modified over-barrier model is presented to study theoretically one and two electron transitions between helium atoms and multiply charged ion collisions at a low-to-intermediate velocity ( ν Bohr ∼ 5 ν Bohr). It is found that the present model can partially reproduce the experimentally obtained velocity dependence of the absolute cross-sections which is also supported by the results of the classical trajectory Monte Carlo (CTMC) method.

ExperimentalM1transition rates in K XI, K XV, and K XVI

Transition probabilities of three magnetic dipole $(M1)$ transitions in multiply charged ions of potassium have been measured using the Livermore electron beam ion trap EBIT-2. Our results for the atomic level lifetimes are $4.44\ifmmode\pm\else\textpm\fi{}0.10 \mathrm{ms}$ for K XI (F-like) ${2s}^{2}{2p}^{5}{}^{2}{P}_{1/2}^{o},$ $4.47\ifmmode\pm\else\textpm\fi{}0.10 \mathrm{ms}$ for K XV (B-like) ${2s}^{2}2p{}^{2}{P}_{3/2}^{o},$ and $7.6\ifmmode\pm\else\textpm\fi{}0.5 \mathrm{ms}$ for K XVI (Be-like) $2s2p{}^{3}{\mathrm{P}}_{2}^{o}.$ The results confirm the accuracy of most predictions to within 3% of ground-state and 7% of excited-state transitions.

Experimental M1 Transition Rates of Coronal Lines from Arx, Arxiv, and Arxv

Transition probabilities of three magnetic dipole (M1) transitions in multiply charged ions of Ar have been measured using the Livermore electron-beam ion trap. Two of the transitions are in the ground con—gurations of Ar XIV (B-like) and Ar IX (F-like), and are associated with the coronal lines at 4412.4 and 5533.4 respectively. The third is in the excited 2s2p con—guration of Be-like Ar XV and produces Ae , the coronal line at 5943.73 Our results for the three atomic level lifetimes are 9.32 ^ 0.12 ms for the Ae . Ar X 2s22p5 level, 9.70 ^ 0.15 ms for the Ar XIV 2s22p level, and 15.0 ^ 0.8 ms for the Ar XV 2P 1@2 2P 3@2 2s2p level. These results diUer signi—cantly from earlier measurements and are the most accurate 3P 2 ones to date. Subject headings: atomic datamethods: laboratory

Partial population inversion for electric-nuclear transitions in multiply charged ions

Specifics are considered of achieving amplification in mixed electronic-nuclear transitions in a multiply charged ion. In particular, the possibility is examined of attaining inversion in such a γ-transition as a result of an electronic state inversion involving no nuclear level inversion.

Influence of the shock-front structure on the nature of luminescence from a recombining laser plasma

Spatial, temporal, and spectral measurements were made of the radiation characteristics of a laser plasma interacting with a plane screen. The angular distribution of the fastest plasma component was constructed, the displacement velocity of the bulk of the plasma was found, the velocity of reflection of the shock wave from the screen was determined, and the propagation velocity of a tongue of electron heating by heat conduction was estimated. The intensity of the continuous spectrum increased somewhat in the conduction heating zone, where there was a fall in the recombination pumping rate (and consequently in the luminescence of the ion lines). A sharp increase in the intensity of the laser plasma recombination luminescence was recorded when a plane screen was placed in the path of its expansion, and this was shown to be due to the structure of the shock front formed in the plasma. An intensification of the recombination filling of the levels in the shock-wave density discontinuity could be used to amplify radiation due to transitions in multiply charged ions.

Prospects for light amplification in the far ultraviolet (review)

A review is given of theoretical and experimental investigations concerned with the feasibility of light amplification in the far ultraviolet (3–50 nm) due to transitions in multiply charged ions. An analysis is made of the most advanced population inversion methods. Experiments in which population inversion was observed or amplification was achieved are examined. The feasibility of developing short-wavelength lasers utilizing recombination systems similar to those achieved for singly charged ions are discussed.

Search for amplification in the far vacuum ultraviolet due to transitions of multiply charged ions in an extended laser plasma

A search was made for amplifications due to transitions in multiply charged ions in an extended plasma. This was done by investigating the spectra of plasma filaments created by subnanosecond laser pulses interacting with various targets. Anomalies were found in the behavior of the intensities of a series of Na IX and C VI lines observed along the filament axis. It was found that these anomalies could be attributed to amplification due to the 2p--4d, 2p--3d, and 2s--3p transitions in the Na IX ion and due to the 3--4 transition in the C VI ion.

Gain in the far vacuum ultraviolet region due to transitions in multiply charged ions

It is shown that a gain of the order of 10–25 cm–1 can be obtained in the 300–700 A range due to the 3s – 3p transition in multiply charged ions with a ground electronic configuration 1s22s22p6. This gain may be obtained as a result of heating of electrons in a plasma by high-power ultrashort light pulses (two-stage plasma heating).

Possibility of constructing a far-ultraviolet laser utilizing transitions in multiply charged ions in an inhomogeneous plasma

Radiative characteristics of a laser plasma are considered. It is shown that a considerable proportion of the absorbed laser energy may be converted into resonance lines of multiply charged ions. Two methods for the utilization of resonance x-ray radiation in the population inversion in a two-component plasma are discussed. In one method, the resonance radiation of one component in the dense core of the plasma is used for selective resonance pumping of some level in the other component in the outer rare region. In the second method, the radiation of ions in the outer layer is used to photoionize ions in the inner core; this produces conditions analogous to those in a supercooled plasma and a population inversion is established. In all cases, the gain may be of the order of 103 cm–1.

Oscillator-strength systematics for low-lying transitions in multiply charged ions

The foil-excitation technique has been used to study atomic lifetimes in a number of homologous atoms with ionic charges up to six. It was observed that even at moderate initial ion energies (approx. 500 keV), some low-lying levels in multiply charged ions are populated with sufficient intensity for lifetime measurements. The relatively low initial ion energies facilitate the spectral-line identification, so line broadening seems to be a minor problem compared to higher initial ion energies. Systematic trends in the ƒ- values derived from the lifetime measurements for n 2S− n 2P and n 2P− n 2D transitions in the Cu I, Ag I and Au I isoelectronic sequences are discussed and compared with earlier measurements for homologous atoms with lower masses. From the present results, ƒ- values for transitions which can not be measured experimentally due to line blending, are derived by interpolation. An extrapolation of the present ƒ- values allows a determination of ƒ- values in highly charged ions with reasonable accuracy.