M Chantepie

The Zn I 4p2 autoionising level widths

The (4p2)3PJ autoionising resonances of neutral zinc were investigated using laser excitation from the (4s4p)3PJ levels populated in a DC discharge. The profiles were recorded using optogalvanic detection. The widths are 0.36 cm-1 for the (4p2)3P1 level, below 0.02 cm-1 for the (4p2)3P0 level and 22.2 cm-1 for the (4p2)3P2 level. These results are in good agreement with theoretical predictions based on a fully relativistic treatment.

120-keV Kr8+ – Li collisions studied by near UV and visible photon spectroscopy

Results of charge‐exchange collisions between Kr8+ ions and lithium are presented. A detailed spectroscopic analysis of recorded data is presented. (AIP)

Time-resolved fluorescence of the 1S0 and 1D2 series of Mg I

The lifetimes of the n1S0 (n=4 to n=10) and n1D2 (n=3 to n=17) states in Mg I have been measured using the time-resolved fluorescence technique following two-photon excitation of the atoms produced in a cell. The results clearly show strong perturbations of the 1D2 series although the 1S0 series is less perturbed. The calculations performed using a central-field method indicate strong interaction with the (3p2) configuration. The strength of this interaction is compared with those occurring in Cd I and Zn I.

Electron capture into N4+(1s2nl) subshells during N5+-Li collisions at 40-120 keV

We have recorded photon spectra during collisions between N5+ ions and lithium atoms in the range 200-600 nm at different projectile energies (40-120 keV). The spectral resolution allowed the determination of capture cross sections of nl subshells with principal quantum numbers n=6, 7 and 8. The experimental results are compared to calculations using the three-body classical trajectory Monte Carlo method (CTMC). On the whole, a good agreement between experimental and CTMC calculated results is obtained. The influence of the projectile core electrons is examined comparing CTMC calculations for the B5+-Li collision system to those for N5+-Li. A small but not negligible core-electron effect is observed which manifests itself mainly in the population of the N4+(ns) subshells.

Polarized light emission during very slow - Li(2s) collisions ()

We report on the polarization of lines emitted by excited ions produced by the single-electron capture process during collisions at very low impact energies (E = 0.1 - 1.0). The polarization degrees of lines corresponding to and transitions were measured and were compared with theoretical polarization degrees obtained from distributions calculated by using the classical trajectory Monte Carlo (CTMC) method. A remarkable energy dependence is observed in both the experimental and theoretical results at very low projectile velocity. A qualitative discussion based on the relative importance of the different dynamical couplings is proposed.

Velocity effect in the l-distribution of the electron capture in collisions of highly charged Ar8+ ions with a Li(2s) target

Abstract The effect of the velocity of the incident ions in the l-distributions of the electron capture in collisions of highly charged Ar8+ ions with a Li(2s) target is studied. These Ar8+Li collisions are experimentally studied by means of near UV and visible photon spectroscopy (200–600 nm) and theoretically analysed by means of the three-body classical trajectory Monte Carlo method. In addition to the effect of the projectile core, we show that the final nl-distributions are, for the most populated n = 8 and n = 9 states, strongly energy dependent.

Velocity and core-electron effects in state-selective electron capture following Ar8+-Li collisions

The effect of the velocity of the incident ions in the nl-distributions of the electron capture in collisions of highly charged Ar8+ ions with a lithium target is studied. These Ar8+-Li(2s) collisions are experimentally studied by means of near UV and visible photon spectroscopy (200-600 nm) in the 1.5-4.5 keV amu-1 energy range and theoretically analysed by means of the three-body classical trajectory Monte-Carlo method. The presence of projectile core-electrons strongly affects the population and collision energy dependence of low l values produced in the electron capture reaction. It is shown that the sigma (nl) partial cross sections (n=8, 9 and l=0, 1, 2) increase with decreasing energies.

Photon emission spectroscopy of single and double electron capture in Ar8+-He or H2 collisions

Ar8+-ion beam collisions, at 160 keV, on He or H2 targets have been studied by photon spectroscopy in the 200-800 nm wavelength range. Strong Delta n=0 lines are observed, due to single and double electron captures.

Experimental wavelengths and term values in N V obtained by high resolution photon spectroscopy

Photon emission of the N5+-Li collision system has been recorded at 75 keV projectile energy using high resolution spectroscopy in the near UV and visible wavelength domain. The experiments yield the resolution of some previously unknown lines in N V which allow a precise determination of the term energies (7g 2G, 7h 2H, 7i 2I, 8g 2G, 8h 2H, 8i 2I, 9g 2G, 9h 2H, 9i 2I, 9k 2K) and the fine structure of the 5d 2D term. These results have previously been known only from calculations (see R. Hallin, Arkiv for Fysik 31, 511 (1966)). The experimental results are in good agreement with the theoretical values. Ten new term values and a new value for the fine structure splitting of the 5d 2D term in N V are proposed.

Study of photon spectra emitted during N5+ ?Li collisions

Spectra in the visible and near ultraviolet wavelength region (200-600 nm) have been recorded during collisions between five times ionized nitrogen ions (produced by an ECR-ion source) and a neutral lithium gas target. Besides the collisional aspects which will be presented elsewhere, the experiments yielded numerous interesting features from a spectroscopic point of view which we present here. Many previously unknown lines show up in our spectra, strong ones amongst them. Most lines can be classified as transitions between 1s2nl configurations in the N V term system produced by a single electron capture process. We also observed transitions between configurations 1s2s(3S)nl with high n and l values. These are populated if an electron is captured by metastable N5+ ions which are known to be produced in an ECR ion source. From line intensities we estimated a fraction of about 5% metastable ions in the N5+ beam. Some new lines in N IV with configurations 1s22s(2S)nl and 1s22p(2P)nl were identified. Those configurations were produced when two electrons were captured by a N5+ projectile.