D. Vernhet

X-ray reflectivities, at low and high order of reflection, of flat highly oriented pyrolytic graphite crystals

Abstract Integrated reflectivities of flat highly oriented pyrolytic graphite crystals have been measured at various energies (5.9 ≤E ≤ 15.10 keV) and for various orders of reflection n (1 ≤n ≤ 5). For low n values, the reflectivity is severely affected by secondary extinction; our results show that the theory of Zachariasen represents the experiment reasonably well, a conclusion reached by other authors for the case of n = 1 reflections. For high n values, the reflectivity is more sensitive to the structure factors temperature correction, a quantity not precisely known. Our measurements are in favour of the larger temperature correction within the range reported in the literature.

Excitation of Kr34+ ions at intermediate velocity

Abstract Total and partial excitation cross sections for 34 MeV/amu Kr34+ ions colliding with various targets (6 ≤ Zt ≤ 40) have been determined from projectile X-ray measurements. The results were compared to the predictions of a method based on Schwingers variational principle.

Alignment of Kr35+ np states in high velocity charge transfer collisions

Abstract Experimental alignments of some Kr35+ np states (n

Charge exchange collisions involving highly stripped ions: Distribution and anisotropy of final state angular momenta

= 4) populated by electron capture in 3 GeV Kr36+ ion-atom collisions are presented. A full comparison with theoretical CDW calculations is performed, which provides a further test of the applicability of this theory at the low side of the high energy range ( v p v i , v f ∼ 2 to 4 ).

Investigation of angular momenta and correlation patterns in doubly excited states populated by low velocity double charge exchange

Abstract In this paper, physical effects responsible for l and m distributions in low energy capture process are discussed and a review of the physical content of various theories is given. Experimental data are reported for l, m capture cross sections for 4 keV u Ne9+ → H2 collisions and compared to theoretical predictions for the F9+ → H case.

Single and double charge exchange processes with low energy multicharged ions

Abstract Autoionization branching ratios of O 6+ doubly excited states are shown to depend sensitively on the K , T and L quantum numbers of these states. A measurement of the decay probabilities to 2s and 2p sublevels has been performed for the (3, 3) and (3, 4) doubly excited states populated in the 1.3 keV/u O 8+ → He collision. A new technique of X-ray, energy gain coincidence has been used. Results are discussed in terms of possible distributions K , L for the doubly excited states.

A method for the determination of angular momenta in single and double capture by low velocity multiply charged ions using energy gain-X-ray coincidence technique☆

Abstract An original method is presented for extracting information on single and double capture processes in low velocity collisions with bare and one-electron projectiles. Experimental data are reported for P(l) distributions in single capture and for the percentage of double capture with respect to the single capture in 10q keV Ne9+ → H2 and Al13 → He systems (v ∼ 0.4 a.u.). The preferential n state populated by double capture (after autoionization) is also deduced.

Charge exchange process with low energy multicharged ions: n, l populations☆

Abstract A new technique is presented providing information on the angular momentum distribution of electrons captured by multiply charged ions and particularly suitable for investigating weak channels: capture in non-dominant n states, double capture. This method is based on coincidence measurements between scattered ions having suffered a given energy gain and X-rays resulting from the decay of excited states formed during the collision. Preliminary results are given for the O 8+ + H 2 collision at 3 q keV.

Alignment of Ne

Abstract Theoretical models for low energy charge exchange collisions of highly charged ions are reviewed in connection with populated final states. A simple experimental method is presented which provides the most populated n level, the percentage of p substates and the mean l value. Results are reported for 10 keV q Al 12+ collisions on H 2 and He.