Localized versus delocalized excitations just above the 3d threshold in krypton clusters studied by Auger electron spectroscopy

MAX-lab, Lund University, P.O. Box 118, SE-221 00 Lund, Sweden.
The Journal of Chemical Physics (Impact Factor: 2.95). 10/2007; 127(12):124314. DOI: 10.1063/1.2770460
Source: PubMed


We present Auger spectroscopy studies of large krypton clusters excited by soft x-ray photons with energies on and just above the 3d(52) ionization threshold. The deexcitation spectra contain new features as compared to the spectra measured both below and far above threshold. Possible origins of these extra features, which stay at constant kinetic energies, are discussed: (1) normal Auger process with a postcollision interaction induced energy shift, (2) recapture of photoelectrons into high Rydberg orbitals after Auger decay, and (3) excitation into the conduction band (or "internal" ionization) followed by Auger decay. The first two schemes are ruled out, hence internal ionization remains the most probable explanation.

Download full-text


Available from: Sergey Peredkov, Nov 10, 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: X-ray absorption spectra of small krypton clusters with average size of ∼15 atoms were measured with Kr2+ ion yields at the Kr 3d5/2 and 3d3/2 region. The second lowest Rydberg transition 3d−16p is redshifted from the corresponding atomic transition, and shows an asymmetric broad shoulder feature. This characteristic feature is attributable to some surface sites with different coordination numbers such as corner, edge and face as previously observed in the Kr 3d photoexcitation and photoelectron spectra. Diffuse Rydberg states are influenced predominantly with induced polarization of the surrounding atoms. On the other hand, the lowest transition 3d−15p is blueshifted, and shows a rather narrow peak. The blueshift arises from short-range repulsive interaction, that is, exchange interaction of the Rydberg electron with the surrounding atoms. The larger coordination number of the nearest neighbor atoms increases both the exchange (blueshift) and induced polarization (redshift) effects. In the higher Rydberg state, the blueshift effect is drastically reduced but the redshift effect is most dominant. Cancelation of these two effects can be expected in the lowest Rydberg transition. The present experimental analysis enables us to discuss the site-dependent and state-dependent exchange interaction.
    Journal of Electron Spectroscopy and Related Phenomena 11/2008; 166(1):16-20. DOI:10.1016/j.elspec.2008.07.010 · 1.44 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A photon-energy-dependent experimental study of the L2,3M2,3M2,3 Auger transitions in argon clusters is presented, and features without atomic counterparts are observed in the spectra up to photon energies at least 30eV above the L2,3 threshold. We propose that these features are due to the process of neighbor-induced recapture, in which the outgoing photoelectron is backscattered by neighboring atoms in the cluster, loses energy in a Bremsstrahlung-like inverse photoemission process, and is recaptured in a Rydberg orbital of the core-ionized atom before Auger decay.
    Physical Review A 12/2008; 78(6):65201-. DOI:10.1103/PhysRevA.78.065201 · 2.81 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this review we describe the development and current status of free clusters studied using core-level spectroscopies. This topic ranges from simple model systems, such as rare gas clusters, to molecular clusters, and clusters of solids, held together by ionic, covalent and metallic bonding.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 03/2009; 601(601):161-181. DOI:10.1016/j.nima.2008.12.222 · 1.22 Impact Factor
Show more