5p 2P Research Articles

Effects of argon-ion bombardment on the properties of the surface layer in spinel crystals of different composition

Ion-induced photon emission (IPE) during bombardment of magnesium aluminate spinel crystals MgO· nAl 2O 3 by 20 keV Ar + ions was studied. The dependence of the yield of particles in specific excited states on the fluence of incident ions in the range of (0.1–1.6)×10 17 ions/cm 2 was measured. It was shown that yield of magnesium and aluminum atoms and ions in most excited states do not depend (or slightly depend) on the fluence of ion bombardment. An exception was found for yields of Mg + ions in the 4s 2S excited state and Al atoms in the 5p 2P 0 excited state leading to emission lines at 292.8 and 669.6 nm, respectively. The yield of particles in these excited states drastically decreases at the start of ion bombardment. Analysis of these results and published data on the bombardment-induced surface modification of spinel crystals allows to elucidate the role of crystal structure and chemical bonding in the formation of some excited states. The dependence of excited state yield (except of Mg and Al indicated above) from spinel crystals of different composition MgO· nAl 2O 3 ( n=1.0, 1.5, 2.0, and 2.5) does not reflect quantitatively the variation of the calculated bulk concentration of constituent atoms in these targets.

Analysis of the 4p64d84f and 4p54d10 Configurations of Xe X and Some Highly Excited Levels of Xe VIII and Xe IX Ions

The spectra of various ions of xenon were investigated in the 70–170 Å region. The earlier analysis of the 4d9–4d85p transitions Kaufman et al., J. Opt. Soc. Am. B 73, 691 (1983) in Rh-like Xe X was confirmed except for the two highest 4d8(1S)5p 2P levels. The 4p64d9–(4p64d85p84f +4p54d10) transitions arrays were studied. We have established 28 new levels belonging to the odd parity system and classified 40 additional lines in Xe X. The spectrum is adequately described by the Hartree–Fock and parametric least-squares-fitting calculations. The resonance transitions from the highly excited 4d9(6p+5f+7p+6f) levels in Pd-like Xe IX and the 4105s 2S–4d95s4f 2P transitions in Ag-like Xe VIII have also been identified. The ionization potential of Xe IX has been calculated to be 1450500±1000 cm-1 (179.85±0.10 eV). The results from all three spectra are in good agreement with the Rh I, Pd I and Ag I isoelectronic sequences data.

Chemical dynamics of the reaction K*(5p 2P)+H2→KH(v=0;J)+H: Electronic orbital alignment effects

We report results from scattering state spectroscopic studies of the excited state reaction K*(5p 2P)+H2→KH(v″,J″)+H. The final state resolved action spectra allow a direct measurement of essential features of the excited state potential surfaces, including regions of local maxima and minima. We observe a pronounced blue-wing–red-wing asymmetry in the reactive to nonreactive branching ratio, peaking in the neighborhood of a strong blue wing satellite. These results show that the dominant reaction pathway passes over a small activation barrier (350±100 cm−1) in Σ+-like orbital alignment. This result is consistent with an electron jump mechanism through a K+H−H ion-pair intermediate. In contrast, approach in Π-like alignment leads predominantly to nonreactive scattering. Our results suggest that a combination of steric and energetic effects determine the major quenching pathways for alkali metal atom-H2 systems.

Strong Dependence of the 2p Photoionization Cross Sectionsof Na Atoms on Valence Electron State

The cross sections and asymmetry parameters β of the 2pelectron single photoionization, shake-up and shake-down processesfrom Na atoms in the ground state and in a number of excited states2p6nl (n = 3, 4, 5 and l ≤ n–1) are calculated using a single channelrelaxed-orbital Hartree–Fock approximation. A strong dependenceof the calculated cross sections on the atomic orbit of the valenceelectron is found. The asymmetry parameters β are sensitive tothe excitation of the valence electron near the threshold ofphotoionization. The single photoionization of the 2p subshell of Naatoms in the 4d 2D, 5p 2P and 5f 2Fstates is found to be about 43, 150 and 105 times lessprobable respectively than the shake-up process.

Sympathetic cooling of stored ions in a penning trap

Two different ion species (Be + and Cd +) were trapped simultaneously in a Penning trap. The Be + ions were directly laser-cooled and the Cd + ions were sympathetically cooled to below 1 K by the Coulomb interactions. The ultraviolet spectra (5s 2S 1/2-5p 2P 3/2, 214.5 nm) of six isotopes of the Cd+ ions were observed.

Elastic and inelastic scattering of electrons from potassium

We have examined elastic and inelastic scattering of electrons from potassium. For the case of elastic scattering, we have compared potential scattering theory and perturbation theory. If one wishes to use the potential scattering approach, it is shown that both the non-local effects of polarization and absorption must be properly modelled to get accurate elastic differential cross sections. The second-order distorted wave results For elastic scattering and excitation of the (4p)2P and (5p)2P states are compared with existing experimental data and a very recent close coupling calculation for energies between 7 and 100 eV.

Fine-structure oscillator strengths for excited-state transitions in Cu-like ions

Transitions originating from excited states in copper-like ions have been studied. Fine-structure oscillator strengths obtained with both the quantum defect orbital (QDO) and its relativistic (RQDO) counterpart are reported for 4p 2P – nd 2D (n = 5, 6), 5p 2P – nd 2D (n = 5, 6), and np 2P – 6s 2S (n = 4, 5 ) absorption transitions. © 1992 John Wiley & Sons, Inc.

Electron-electron coincidence studies of the decay of photoexcited rare gas core resonances

The two-electrons emitted upon the two-step decay of the photoexcited Xe 4d 9 6p; Kr 3d 9 5p and Ar 2p 5 4s resonances have been detected in coincidence. The complex spectra could be unraveled and first- and second-step Auger lines identified unambigously.

ESR and Optical Absorption of Ag in a N2 Matrix

AbstractAg atoms isolated in N2 matrices were studied by simultaneous observation of optical absorption and electron spin resonance (ESR). In matrices with low Ag/N2 ratios two ESR signals were observed, both of which could be correlated to the well known absorption triplet corresponding to the 5s 2S → 5p 2P resonance transition. One of the two ESR signals disappeared irreversably upon annealing up to 20 K. The stable species is attributed to Ag atoms in a nanocrystalline environment whereas the unstable species corresponds to atoms in the non‐crystalline regions between the crystallites. In higher doped matrices a new Ag spectrum showed up, both in the optical absorption and in the ESR. It is assigned to Ag atoms with near‐by complexes, possibly Ag clusters.

Tunable, frequency narrowed Nd 3+-doped fiber laser for excitation of the 5p 2P [formula omitted]-4d 2D [formula omitted] transition in Sr +

A narrow linewidth, cw Nd 3+ doped fiber laser is described for application to the excitation of the 1092 nm, 5p 2P 1 2 -4d 2 D 3 2 transition in Sr +. The laser incorporates a gradient-index lens as an intra-cavity beam collimator and employs a grating together with a series of etalons as frequency selective and tuning elements. Tunable laser output in the region of 940 nm is also described. A demonstration of excitation on the Sr + transition is shown by observing the optical pumping of Sr + in an optogalvanic discharge.

Photolysis of highly vibrationally excited CF 3I molecules by visible laser light

Visible (450 nm) and IR laser photolysis processes of CF 3I molecules are studied through state-selective resonant multiphoton ionization (RMPI) of atomic iodine. Sufficiently strong vibrational excitation of CF 3I in the IR field of a TEA CO 2 laser is found to make possible 450 nm dye-laser photolysis of the molecules, the estimated photolysis cross section being around 5 × 10 −21 cm 2. It is shown that in the case of steady-state IR MP dissociation of CF 3I, the RMPI detection of the excited iodine (5p( 2P 1 2 )) appearing as a result of 450 nm photolysis of the CF 3I molecules enables one to measure on a real-time scale the fraction of molecules that failed to dissociate under IR radiation.

Level isotope shifts of indium 113 and 115

The isotope shifts of several Doppler-free two-photon lines of the series 5p 2P 1 2 , 3 2 - np 2P 1 2 , 3 2 ( n=16–43) and 5p 2P 1 2 - nf 2F 5 2 ( n= 8–14) in 113, 115 In have been measured with a thermionic heat-pipe diode modified for investigations of low pressure and strongly alloying elements. From the experimental data the residual level isotope shift (RLIS) of the 5p 2P 1 2 and 5p 2P 3 2 ground states have been extracted which show a very slight J-dependence. Taking into accou nt these data the RLIS of the 6 and 7s 2S 1 2 levels could be found from transition isotope shift data of other groups.

OPTICAL-OPTICAL DOUBLE RESONANCE EXPERIMENTS WITH GALLIUM AND INDIUM ATOMS VIA OPTOGALVANIC DETECTION

Looking at the transition sequences 5s2 5p 2P°1/2 [MATH] 5s2 6s 2S1/2 [MATH] 5s2 8p 2P°1/2 5s2 5p 2P°1/2 [MATH] 5s2 6s 2S1/2 [MATH] 5s2 8p 2P°3/2 in the indium atomic spectra and at similar sequences 4s2 4p 2P°3/2 [MATH] 4s2 5s 2S1/2 [MATH] 4s2 6p 2P°1/2 4s2 4p 2P°3/2 [MATH] 4s2 5s 2S1/2 [MATH] 4s2 6p 2P°3/2 in the gallium atomic spectrum and using two single mode tunable cw-dye- lasers, optical-optical double resonance measurements were performed. The atoms were introduced by sputtering in a hollow-cathode plasma which could be illuminated by the two collinear laser beams propagating either parallel or antiparallel.With both elements measurements were done with the natural isotopic mixture ; in the case of gallium additional experiments with highly enriched gallium-71 were performed. Results concerning the hyperfine interaction constants of the 8p 2P° and 6p 2P° levels and the isotopic shifts of the lines will be given.

Closed N-shell alkali spectra

Term values and ionization potentials have been calculated for several ions in the promethium ( N = 61) isoelectronic sequence. As the nuclear charge is increased, the ground configuration changes from 4f 135s 2 to 4f 145s giving the upper portion of the sequence an alkali-like character. According to our most recent Hartree-Fock calculations with first-order relativistic corrections, the ground term is 5s 2S for Z > 77 (Ir XVII) and the first excited term is 5p 2P 0 for Z > 84 (P 0 XXIV). Comparisons are made with calculations of Cowan in W XIV. The prospects for observation of these spectra in fast ion beams are discussed.

Direct determination of ratios of electron and Penning excitation rates for Cd(II) excited states in the positive column He-Cd+ laser discharge

A new method has been developed in which the author can determine ratios of electron and Penning excitation rates for Cd(II) excited states directly by superposing quasi-CW and CW excitations. In positive column He-Cd+ laser discharges, the ratios have been determined and it has been proved that the stepwise excitation process exceeds the Penning excitation process for the laser upper states 5s2 2D and also the laser lower states 5p 2P under the discharge conditions for laser action.

Determination of the Penning excitation cross-sections of individual Cd(II) states for He metastable atoms using Penning electron spectroscopy

The relative Penning excitation rates for the individual Cd(II) states by He 21S metastable atoms as well as He 23S metastable atoms were measured separately. The absolute Penning excitation cross-sections for exciting individual Cd(II) states by impact of He 21S atoms were determined by making use of the absolute Penning excitation cross-sections for the Cd(II) states excited by He 23S atoms and Penning collisions between He metastable atoms and Ar atoms. These cross-sections sigma s(M) for Cd(II) states M by He 21S atoms are as follows: sigma s(5s 2S12/)=3.9*10-15 cm2; sigma s(5p 2P)=0.51*10-15 cm2; sigma s(5s2 2D52/)=0.94*10-15 cm2; sigma s(5s2 2D32/)=1.1*10-15 cm2; sigma s(6s 2S12/, 5d 2D)=0.85*10-15 cm2.

A study of the [formula omitted] Rydberg series in neutral indium by means of two-photon laser spectroscopy

The 5p 2P 3 2 − np 2P 1 2 , 3 2 two-photon transitions in neutral indium, with 25 ⩽ n ⩽ 43, have been studied by using a pulsed dye laser. The fine structure of the upper levels has been resolved for the first time and shows a hydrogenic behaviour over the series. The accurately determined quantum defects confirm the value of the ionization limit, 46670.107 cm -1, derived previously from the 2S series. Discrepancies between our results and those obtained in earlier investigations are discussed. The relation predicted by theory between the two-photon transition probability and the energy difference between the real and the virtual intermediate level has been verified experimentally.

A frequency-doubled frequency-stabilized cw ring dye laser for spectroscopy: A study of the λ = 293.3 nm transition in In1

In this letter a frequency-doubled frequency-stabilized CW ring dye laser for the wavelength region 292–305 nm is described. 500 μW U.V. power combined with a 2 MHz linewidth and a 7 GHz scanwidth has been obtained by intracavity frequency doubling in an ADA crystal. The set-up has been tested on the hyperfinestructure of the λ = 293.3 nm transition 5p 2P 3 2 → 7s 2S 1 2 in In1.

Lifetimes for Low-lying Levels in Zn I and Zn II

Lifetime measurements using the beam-foil technique have been made for levels in Zn I and Zn II. The following results (in ns) were obtained: ZnI, 4s4p 1P (1.33 ± 0.07), 4s4d 1D (20.5 ± 1.5), 4s4d 3D (5.4 ± 0.6); Zn II, 4p 2P (2.07 ± 0.20), 4d 2D (1.40 ± 0.15), 5s 2S (1.8 ± 0.2), 5p 2P (17 ± 2). These results are compared with previous experimental and theoretical results and the origins of certain disagreements are analyzed.

Collisional quenching of K * (4p 2p) and K * (5p 2p by H 2O, CF 4, and CH 4

Rate constants are reported for collisional quenching of K * (4p 2p and K * (5p 2p) by H 2O, CF 4 and CH 4. The K * (4p 2p or K *(5p 2p) is produced by photodissociation of K1 vapor at 2450 Å or 1925 Å, respectively. As for Na * (3p 2p, H 2O, CF 4, and CH 4 are very inefficient at quenching K * (4p 2p); however, they are very efficient at quenching K * (5p 2p).