First Photoexcitation Measurements andR-Matrix Calculations of Even-Parity Hollow States in Laser-Excited Lithium Atoms

Angle-Resolved Photoelectron Spectrometry Studies of the Autoionization of the2s22p2P<

“…The lowestenergy triply excited state in which all three electrons have the same principal quantum number ͑n 3͒ was also measured [13,14]. Theoretical calculations involving various approximations (R matrix [10][11][12][13], saddle point [15]) were carried out providing good agreement with the measured excitation energies as well as with the partial cross sections. More recently, a new approach using hyperspherical coordinates was developed [16] in an attempt to establish a systematic classification of the triply excited states and to visualize the correlated electron motions in the case of the intrashell states for n 2.…”

“…Angle-resolved photoelectron spectra were also recorded at some fixed photon energies. The theoretical approach is based on the R-matrix method already described [10][11][12][13] and is here extended to provide differential cross sections and b parameters.…”

“…Most recently, the investigation of this system received strong impetus from the use of a third generation storage ring delivering high-brightness photon beams in the photon energy range (140-200 eV). Highresolution partial cross sections were determined for triple excitation of lithium atoms [11,12] including a classification of many of the states into Rydberg series. The lowestenergy triply excited state in which all three electrons have the same principal quantum number ͑n 3͒ was also measured [13,14].…”

Photoionization of laser-excited caesium atoms above the 4d ionization threshold

“…Those pioneering studies were very important to show the potential of such experiments. With the development of third generation light sources the available photon flux and resolution have improved, but the main experimental difficulties -low target density and the risk of contamination due to a highly reactive sample -have remained unchanged [3,4,5,9]. Investigations of laser-excited atoms using high resolution have been essential to unravel the complexity of the satellite structure in the np valence ionization of Rubidium [11] and Cesium [12].…”

“…Alkali metals are however very reactive, thus the target densities have to be kept relatively low in order to avoid contamination of the experimental setup. High resolution studies were started only in the last 15 years or so with the advent of third generation light sources which provide a sufficiently high flux to offset the low target concentration [4,5,6,7]. Theoretically alkali metals are appealing, because of their hydrogen-like electronic structure with only one electron in an s-orbital outside a noble gas closed shell configuration.…”