2p2 States Research Articles

Doubly-resonant coherent excitation of HCI planar channeled in a Si crystal

We investigated resonant coherent excitation of H-like Ar17+ and He-like Ar16+ ions planar channeled in a Si crystal under the V-type and ladder-type double resonance conditions. In both cases, we observed distinct enhancement in the ionized fraction of the transmitted ions when the double resonance conditions were satis.ed. In the ladder-type configuration, the enhancement indicates that the doubly-excited 2p2 state of He-like Ar16+was produced through doubly-resonant coherent excitation.

The Calculation of the Line Strengths for Magnetic Dipole Transitions Between the 2s2, 2s2p and 2p2 States in Be-like Ions

In this paper we derive a simple approximation to calculate the line strengths for magnetic dipole transitions between the 2s2, 2s2p and 2p2 states of Be-like ions. This approximation only requires a knowledge of the coefficients in the expansion of the configuration interaction wave functions of the states involved in the transition and Wigner 6-j symbols. Results are obtained for a range of Be-like ions from B II to K XXXIII. There is very good agreement between our approximate results and the results of the full calculations of Kingston and Hibbert (2000 J. Phys. B: At. Mol. Opt.Phys. 33 81). The only major differences between the two calculations occur for B II.

Breit-Pauli calculations of the Einstein rate coefficients for magneticdipole, electric quadrupole and magnetic quadrupole transitions in Be-likeions

The Einstein rate coefficients for magnetic dipole (M1), electricquadrupole (E2) and magnetic quadrupole (M2) transitions between all ofthe 2s2, 2s2p and 2p2 states are calculated for a number of Be-like ions from B II to Kr XXXIII. The Einstein ratecoefficients were calculated using two sets of configuration-interactionwavefunctions. The CIV3 code is used to generate both sets ofwavefunctions, one calculation uses only 60 configurations, the othermuch larger calculation uses almost 5000 configurations. In bothcalculations relativistic effects were included using the Breit-Pauliapproximation. Where possible the results are compared with earliercalculations. For some transitions there are considerable differencesbetween our calculations and earlier calculations, particularly at lowvalues of the nuclear charge Z.

The role of metastable atoms in argon-diluted silane radiofrequency plasmas

The evolution of the argon metastable states density has been studied by absorption spectroscopy in power-modulated plasmas of argon and a mixture of 4% silane in argon. A small concentration of silane suppresses the argon metastable states density by molecular quenching. This molecular quenching adds to the electronic collisional dissociation to increase the silane dissociation rate as compared with pure silane plasmas. Using time-resolved emission spectroscopy, the role of metastable states in excitation to the argon 2P2 state has been determined in comparison with production from the ground state. In silane plasmas, emission from SiH* is due essentially to electron impact dissociation of silane, whereas in 4% silane-in-argon plasmas, emission from SiH* seems to be due to electron impact excitation of the SiH ground state. These studies demonstrate that argon is not simply a buffer gas but has an influence on the dissociation rate in plasma-assisted deposition of amorphous silicon using argon-diluted silane plasmas.

Electric quadrupole transitions in the beryllium isoelectronic sequence

Electric quadrupole transition probabilities for transitions between the 2s2, 2s2p, and 2p2 states in the beryllium isoelectronic sequence are evaluated using configuration interaction wavefunctions for 6≤Z≤26. It is found that the contribution from the electric quadrupole transitions is negligible and will not be an important process in any laboratory or astrophysical process.

Magnetic quadrupole transitions in the beryllium isoelectronic sequence

Configuration interaction wavefunctions are used to evaluate magnetic dipole transitions between the 2s2, 2s2p, and 2p2 states in the beryllium isoelectronic sequence. It is found that the contribution from the magnetic dipole transitions is negligible, even for moderately high Z and will not be an important process in any laboratory or astrophysical plasma. Some significant differences from previous calculations are obtained.

Spin-orbit electric dipole transmissions in beryllium-like ions

We have used configuration interaction wavefunctions to calculate energy levels, wavelengths, oscillator strengths and transition probabilities for spin-orbit electric dipole transitions between the 2s2, 2s2p, and 2p2 states in beryllium-like ions (Z = 6–10). Some significant differences with previous calculations are obtained. A common set of radial functions is used.

Spektroskopische Untersuchungen über das thermodynamische Gleichgewicht der Anregung in den Plasmen kurzdauernder Impulsentladungen

The light emission of gases conducting electric discharges is of considerable complexity. The observed phenomenas are controlled to a great part by the electric parameters of the circuit, as well as by the time constants of the specific plasma properties as the relation times for reaching Maxwellian distribution and thermal equilibrium of electrons, ions, and atoms. The influence of the nonequilibrium between the excitation and the electron temperature on the population of states was studied in short time discharges by means of singulet and triplet lines of elements of the second group of the periodic system. In these discharges a nonequilibrium was found between the excitation and the electron temperature. While the time constant measured for the cooling of the electron gas was found to 7·10−7 s in a discharge switched off 9·10−7 s past the ignition the minimal time constant of relaxation of excitation is equal to the life time of the 2p2 state — this value of cadmium being 2.4·10−6 s -.The use of Boltzmann and Saha equation must be considered very carefully in this type of short time discharges.

Collisions of the Second Kind with Excited Mercury Atoms in the 2P State

A NUMBER of experiments have recently been performed by various experimenters in which a mixture of gases containing mercury vapour as one constituent has been illuminated by light from a water-cooled quartz mercury arc. In interpreting the results of these experiments it has generally been assumed that the following process takes place. Mercury atoms first absorb radiation λ2536, an electron thereby being raised to the 2p2 state. Having reached this excited state the mercury atom may collide with one of the other atoms or molecules present and transfer its potential energy over to the other atom or molecule. The energy thus transferred may do one of several things. It may cause a molecule to dissociate; it may excite the colliding molecule or atom; it may all be changed into thermal kinetic energy of the two colliding bodies; or it may do combinations of the above.