4d-inner-shell ionization of Xe+ ions and subsequent Auger decay

We have studied Xe+4d inner-shell photoionization in a direct experiment on Xe+ ions, merging an ion and a photon beam and detecting the ejected electrons with a cylindrical mirror analyzer. The measured 4d photoelectron spectrum is compared to the 4d core valence double ionization spectrum of the neutral Xe atom, obtained with a magnetic bottle spectrometer. This multicoincidence experiment gives access to the spectroscopy of the individual Xe2+4d−15p−1 states and to their respective Auger decays, which are found to present a strong selectivity. The experimental results are interpreted with the help of ab initio calculations.1\. Auflag

Effect of temperature in bands structure, effective mass and correlation with magneto-transport properties in a nanostructure far-infrared detector superlattice

We report here the effect of temperature in bands structure performed in the envelope function formalism, effective mass and magneto- transport properties of n-type HgTe (d(1)=8.6 nm) /CdTe (d(2)=3.2 nm) superlattices (SLs). When d(2) increase the gap E-g(Gamma) decrease to zero, at the transition semiconductor to semimetal conductivity, and become negative accusing a semimetallic conduction after the point T'(d(2)T', ET'). d(2)T' and ET' increases with temperature and removes the transition to higher d(2). Eg(Gamma) increases from 48 meV at 4.2 K to 105 meV at 300K. The Fermi level is constant (E-F(2D) approximate to 90 meV) until 77K and increases to 167 meV at 300K. Our Theoretical calculations have provided good agreement with the experimental data. The formalism used here predicts that the system is semiconductor for our ratio d(1)/d(2) = 2.69, when d(2) < 100 nm. In our case, d(2)=3.2 nm and E-g (Gamma,77K) = 60 meV so this sample is a two-dimensional far-infrared detector semiconductor (12 mu m<lambda(c)<28 mu m).Idbaha, A.; Nafidi, A.; Khallouq, K.; Charifi, H.; Chaib, H.; Marí, B.; Mollar García, MA.... (2013). Effect of temperature in bands structure, effective mass and correlation with magneto-transport properties in a nanostructure far-infrared detector superlattice. Journal of Optoelectronics and Advanced Materials. 15(11-12):1275-1279. http://hdl.handle.net/10251/84267S127512791511-1

Multielectron spectroscopy:energy levels of Kn⁺ and Rbn⁺ ions (n = 2, 3, 4)

Abstract A magnetic bottle time-of-flight spectrometer has been used to perform spectroscopy of K n⁺ and Rb n⁺ states with ionization degrees n of 2, 3 and 4. Energy levels are directly measured by detecting in coincidence the n electrons that are emitted as a result of single photon absorption. Experimental results are compared with the energies from the NIST atomic database and ab initio multiconfiguration Dirac–Fock calculations. Previously unidentified 3p ⁴(³P)3d ¹ ⁴D energy levels of K²⁺ are assigned

4d-inner-shell ionization of Xe+ ions and subsequent Auger decay

Abstract We have studied Xe+4d inner-shell photoionization in a direct experiment on Xe+ ions, merging an ion and a photon beam and detecting the ejected electrons with a cylindrical mirror analyzer. The measured 4d photoelectron spectrum is compared to the 4d core valence double ionization spectrum of the neutral Xe atom, obtained with a magnetic bottle spectrometer. This multicoincidence experiment gives access to the spectroscopy of the individual Xe2+4d−15p−1 states and to their respective Auger decays, which are found to present a strong selectivity. The experimental results are interpreted with the help of ab initio calculations

Auger decay of the 3d hole in the isoelectronic series of Br, Kr⁺, and Rb2⁺

Abstract The Auger decay process of the 3d5/2 hole is studied experimentally and theoretically along the isoelectronic Br, Kr⁺, and Rb2⁺ series with electron configuration [Ar] 3d⁹4s²4p⁶. The experimental results consist of multielectron coincidence data measured from all three elements and conventional high-resolution Auger spectrum for the Br case. Theoretical interpretation was done by using multiconfiguration Dirac-Fock calculations. It is found that the decay rate of two-Auger-electron emission increases along the series in the direction of decreasing nuclear charge. Also, complexity of the Auger spectrum follows the same trend, requiring a drastic increase to the size of the configuration space for describing the observed spectra

Core-hole spectator Auger decay

Abstract For an atomic state with two electrons missing from different core orbitals one may assume that the deeper hole decays first. However, it is quite probable that the double core-hole state will decay by emission of a slow Auger electron where the deeper core hole remains a spectator, especially if the outer core hole can be filled by Coster-Kronig transition, while the deeper cannot. We study here the competition of both Auger decay channels in a model system, the 1s2s2p⁶(3s/3p) states of Ne⁺ ions. As the phenomenon can take place in any decay chain involving multiple core-excited states it can be critical to understand the ion yields, the electron and x-ray emission spectra, and the molecular fragmentation

Evidence of Extreme Ultraviolet Superfluorescence in Xenon

We present a comprehensive experimental and theoretical study on superfluorescence in the extreme ultraviolet wavelength regime. Focusing a free-electron laser pulse in a cell filled with Xe gas, the medium is quasi-instantaneously population inverted by 4d-shell ionization on the giant resonance followed by Auger decay. On the timescale of ∼10  ps to ∼100  ps (depending on parameters) a macroscopic polarization builds up in the medium, resulting in superfluorescent emission of several Xe lines in the forward direction. As the number of emitters in the system is increased by either raising the pressure or the pump-pulse energy, the emission yield grows exponentially over four orders of magnitude and reaches saturation. With increasing yield, we observe line broadening, a manifestation of superfluorescence in the spectral domain. Our novel theoretical approach, based on a full quantum treatment of the atomic system and the irradiated field, shows quantitative agreement with the experiment and supports our interpretation

Evidence of Extreme Ultraviolet Superfluorescence in Xenon

We present a comprehensive experimental and theoretical study on superfluorescence in the extreme ultraviolet wavelength regime. Focusing a free-electron laser pulse in a cell filled with Xe gas, the medium is quasi-instantaneously population inverted by 4d-shell ionization on the giant resonance followed by Auger decay. On the timescale of ∼10 ps to ∼100 ps (depending on parameters) a macroscopic polarization builds up in the medium, resulting in superfluorescent emission of several Xe lines in the forward direction. As the number of emitters in the system is increased by either raising the pressure or the pump-pulse energy, the emission yield grows exponentially over four orders of magnitude and reaches saturation. With increasing yield, we observe line broadening, a manifestation of superfluorescence in the spectral domain. Our novel theoretical approach, based on a full quantum treatment of the atomic system and the irradiated field, shows quantitative agreement with the experiment and supports our interpretation