We have studied the K-shell emission of an Al plasma which was generated by focusing a high contrast 150 fs laser pulse at a wavelength of 395 nm and intensity of 5 3 10 17 W͞cm 2 on a flat Al target tamped by a thin surface layer of MgO. The measured resonance lines (Ly a , He a , and He b ) and their Li-like and He-like satellites are extremely broadened and show a red polarization shift. Analysis of the Ly a and He b satellites yields an electron temperature of ഠ300 eV and an electron density of ͑5 10͒ 3 10 23 cm 23 . [S0031-9007(99)09405-3] PACS numbers: 52.50. Jm, 52.25.Nr, 52.70.Kz One fascinating aspect of the interaction of intense, ultrashort-duration laser pulses with matter is the possibility to generate plasmas at solid state density at high temperatures in the range 0.1 to 1 keV. Under these conditions the ion coupling parameter G [1] exceeds one and the plasma is thus in a strongly coupled state [2]. Such plasmas are of particular interest in inertial confinement fusion (ICF) and astrophysics. For example, it is possible to study the x-ray opacity of matter under conditions found in stellar interiors [3]. The importance for ICF originates from the fact that fs-laser generated plasmas approach temperatures and densities similar to the values currently attained in indirect drive experiments [4] and may therefore be of interest to investigate x-ray spectroscopy diagnostics needed for ICF plasmas [5]. In contrast to ICF plasmas, which require huge laser facilities, fs-laser plasmas can be generated by small tabletoplike lasers with a high repetition rate.Here we report an experiment in which we focused a frequency doubled 150-fs Ti-Sapphire laser on tamped targets, which consisted of solid Al covered by a thin surface layer of MgO. We measured the Al K-shell emission by means of time-integrated high resolution crystal spectroscopy. The resonance and satellite lines were considerably broader than previously reported [6][7][8][9]. For the detailed spectral analysis, we used simultaneously the He-like satellites of the Ly a line and the He b line which is strongly merged with its Li-like satellites. To our knowledge these features have not been considered in previous studies of the x-ray emission from fs-laser plasmas. Our analysis indicates that we achieved a higher density compared to previous experiments where the electron density did not exceed a few times 10 23 cm 23 . We attribute this result to the fact that we avoided early expansion by using a high contrast fs-laser pulse and tamped targets. Also the short wavelength of 395 nm may be helpful because it leads to absorption of the laser at a high critical density (n c 7.2 3 10 21 cm 23 ). Altogether, it was thus possible to produce ultrafast heating of solid Al before any significant expansion took place (i.e., isochoric heating).The ATLAS Ti-Sapphire laser at the MPQ-Garching was used to produce pulses with 150 fs (FWHM), and 200 mJ at l 790 nm. To achieve a high contrast ratio, we frequency doubled the pulses and obtained 65-75 mJ at l 395 nm. ...
This is the published version of a paper published in Physical Review A. Atomic, Molecular, and Optical Physics. Citation for the original published paper (version of record):Andersson, E., Fritzsche, S., Linusson, P., Hedin, L., Eland, J H. et al. (2010) Multielectron coincidence study of the double Auger decay of 3d-ionized krypton.Physical Review A. Atomic, Molecular, and Optical Physics, 82(4) Multielectron coincidence data for triple ionization of krypton have been recorded above the 3d ionization threshold at two photon energies (140 and 150 eV). Three principal transition pathways have been observed, two involving double Auger transitions from Kr + , and one involving single Auger transitions from Kr 2+ created by direct single-photon double ionization. The decay of the 3d 9 2 D 5/2,3/2 states in Kr + has been analyzed in some detail and is found to be strongly dominated by cascade processes where two electrons with well-defined energies are emitted. The decay paths leading to the 4s 2 4p 3 4 S, 2 D, and 2 P states of Kr 3+ are analyzed and energies of seven intermediate states in Kr 2+ are given. A preliminary investigation of the decay paths from Kr + 3d 9 4p 5 nl shake-up states has also been carried out.
Nitrogen and oxygen K emission spectra of glycine in the form of anions, zwitterions, and cations in aqueous solution are presented. It is shown that protonation has a dramatic influence on the local electronic structure and that the functional groups give a distinct spectral fingerprint.
Double photoionization spectra of the CS 2 molecule have been recorded using the TOF-PEPECO technique in combination with synchrotron radiation at the photon energies h = 220, 230, 240, 243, and 362.7 eV. The spectra were recorded in the S 2p and C 1s inner-shell ionization regions and reflect dicationic states formed out of one inner-shell vacancy and one vacancy in the valence region. MCSCF calculations were performed to model the energies of the dicationic states. The spectra associated with a S 2p vacancy are well structured and have been interpreted in some detail by comparison to conventional S 2p and valence photoelectron spectra. The lowest inner-shell-valence dicationic state is observed at the vertical double ionization energy 188.45 eV and is associated with a ͑2p 3/2 ͒ −1 ͑2 g ͒ −1 double vacancy. The spectrum connected to the C 1s vacancy shows a distinct line at 310.8 eV, accompanied by additional broad features at higher double ionization energies. This line is associated with a ͑C 1s͒ −1 ͑2 g ͒ −1 double vacancy.
Final-state trication spectra and electron distributions produced by soft x-ray single-photon triple ionization of rare gas atoms have been obtained by a multiple-coincidence technique using storage-ring synchrotron radiation. The technique uses electron time of flight with ion detection to overcome the problem of high repetition rates in single-bunch operation. A correction needed to the triple-ionization energy of Kr currently listed in standard tables is confirmed, and the method's ability to examine the three-electron distributions, characterizing the ionization mechanisms and post-collision interactions, is illustrated.
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