Segolene Diehl

NEW HIGH-RESOLUTION MEASUREMENTS OF DOUBLY EXCITED STATES OF LI+

We present new results for the doubly excited states Li+(nln´l´) of singly ionized lithium which arise from the measurements of the Auger decay of these states to Li++ ground state ions. Primary excitation of the doubly excited states is achieved by photon impact on neutral lithium atoms and therefore the experiment probes directly the double-shakeup photoionization process h+LiLi+**+e-. Detection of the individual Li+ Auger decay lines provides information on the energies and widths of many doubly excited levels of the ion, including the lowest lying (3l,3l´) state. Classifications are made using recent theoretical calculations.

Complete description of 3p photoionization in calcium

Within the dipole approximation and the LS-coupling limit 3p photoionization in atomic calcium is described completely by two matrix elements and one relative phase. These three parameters are extracted from experimental observables and compared with theoretical calculations (RRPA transformed to the non-relativistic limit) for photon energies around the Cooper minimum in the 3pd channel. Taking into account the intensity-borrowing model, excellent agreement between theoretical and experimental data is found.

Hollow-atom - hollow-ion decay routes of triply excited lithium: first Auger results and a comparison with R-matrix calculations

We present the first photoelectron results for hollow-atom - hollow-ion decay paths of triply excited lithium, in which the hollow lithium atoms decay via hollow and then to ions. The high-resolution data, obtained at the 9.01 beamline of the Advanced Light Source at Berkeley, provide considerable insight into the decay pattern of the various hollow lithium resonances. Tracking the secondary Auger decays as functions of the incident photon energy provides new data on triply excited resonances. The results compare favourably with recent advanced R-matrix calculations. Detection of the individual Auger decay lines also provides information on the energies and widths of a number of doubly excited levels of the ion.

Photoelectron spectroscopy studies of hollow lithium states

Abstract Hollow lithium states photoexcited by synchrotron radiation have been studied by electron spectroscopy. Measured values of their energies and widths are found to be in excellent agreement with saddle-point calculations. The experimental energy dependence of the partial cross-sections agrees very well with R -matrix theory. This review presents a short summary of the present status of the experiments, including recent discoveries such as the observation of a doubly hollow state and several Rydberg series.

Dynamical and relativistic effects in experimental and theoretical studies of inner-shell photoionization of sodium

High-resolution measurements for inner-shell photoionization of Na are presented along with Breit?Pauli R-matrix calculations. The results show excellent agreement, and give insight into the nature and importance of the various relativistic and correlation effects on the inner-shell process.

Photoelectron spectroscopy experiments on singly charged positive-ions using synchrotron radiation

Abstract The first angle-resolved photoelectron spectroscopy experiments on singly charged ions using synchrotron radiation are described. The feasibility of these experiments has been demonstrated for resonant photoionisation of Ca+ ions by use of the high flux of photons available from an undulator. These experiments open new opportunities for the detailed study of photoionisation processes in ionic species.