scholarly journals Auger Electron?Ion Coincidence Studies to Determine the Pathways in Soft X-ray Induced Fragmentation of Isolated Molecules

1986 ◽  
Vol 39 (5) ◽  
pp. 633 ◽  
Author(s):  
W Eberhardt ◽  
EW Plummer ◽  
In Whan Lyo ◽  
R Reininger ◽  
R Carr ◽  
...  
Keyword(s):  
Auger Electron ◽  
Core Hole ◽  
Final State ◽  
Auger Electrons ◽  
X Ray ◽  
Fragment Ions ◽  
Valence Electrons ◽  
Molecular Bond ◽  
Doubly Charged ◽  
Insight Into

We report a coincidence .experiment between energy selected Auger electrons and the ions produced in the events following the absorption of a soft X-ray photon by a CO molecule. This study allows us to correlate specific double hole final state configurations of the Auger decay of a core hole in this molecule with the production of fragment ions, thus giving new experimental insight into the potential energy curves of the doubly charged molecular ion and the involvement of individual valence electrons into the molecular bond in general.

scholarly journals Circular Dichroism in Cu Resonant Auger Electron Diffraction

2016 ◽  
Vol 230 (4) ◽  
Author(s):  
Fumihiko Matsui ◽  
Naoyuki Maejima ◽  
Hirosuke Matsui ◽  
Hiroaki Nishikawa ◽  
Hiroshi Daimon ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Quantum Number ◽  
Auger Electron ◽  
Polarized Light ◽  
Core Hole ◽  
Initial State ◽  
Final State ◽  
Shift Measurement ◽  
Auger Electrons ◽  
The Core

AbstractUpon a core level excitation by circularly polarized light (CPL), the angular momentum of light, i.e. helicity, is transferred to the emitted photoelectron. This phenomenon can be confirmed by the parallax shift measurement of the forward focusing peak (FFP) direction in a stereograph of the atomic arrangement. The angular momentum of the emitted photoelectron is the sum of CPL helicity and the magnetic quantum number (MQN) of the initial state that define the quantum number of the core hole final state. The core hole may decay via Auger electron emission, where in this two electron process the angular momentum has to be conserved as well. Starting from a given core hole, different Auger decay channels with different final state energies and angular momenta of the emitted Auger electrons may be populated. Here we report the observation and formulation of the angular momentum transfer of light to Auger electrons, instead of photoelectrons. We measured photoelectron and Auger electron intensity angular distributions from Cu(111) and Cu(001) surfaces as a function of photon energy and photoelectron kinetic energy. By combining Auger electron spectroscopy with the FFP shift measurements at absorption threshold, element- and MQN-specific hole states can be generated in the valence band.

CORE-HOLE EFFECT IN THE Ce L3 X-RAY ABSORPTION SPECTRA OF CeO2 AND CeFe2: NEW EXAMINATION BY USING RESONANT X-RAY EMISSION SPECTROSCOPY

2013 ◽  
Vol 27 (16) ◽  
pp. 1330012 ◽  
Author(s):  
A. KOTANI
Keyword(s):  
Absorption Spectra ◽  
Ground State ◽  
Theoretical Calculations ◽  
Emission Spectra ◽  
Core Hole ◽  
Final State ◽  
X Ray ◽  
The Core ◽  
X Ray Absorption ◽  
Hole Effect

We consider two different resonant X-ray emission spectra for Ce compounds: Ce 3d to 2p X-ray emission (denoted by 3d-RXES) and valence to 2p X-ray emission (v-RXES), both of which follow the Ce 2p to 5d resonant excitation. We propose that the comparison of the 3d- and v-RXES spectra is a new powerful method of directly detecting the core-hole effect in the final state of Ce L 3 X-ray absorption spectra (XAS). We applied this method to recent experimental RXES spectra for CeO 2 and CeFe 2, and showed unambiguously that the core-hole effect should be essential in the XAS of both materials. This result is confirmed by theoretical calculations, which reproduce well the experimental RXES and XAS spectra. We conclude that the ground state of CeO 2 is in the mixed state of 4f0 and [Formula: see text] configurations, where [Formula: see text] is a ligand hole, instead of a pure 4f0 configuration which was proposed recently by first-principles energy band calculations. Also, we conclude that the double peaks observed in L 3 XAS of CeFe 2 are caused by the 4f0 and 4f1 configurations, which are mixed in the ground state but separated in energy by the large core-hole potential in the final state of XAS.

Study of N-bridged diiron phthalocyanine relevant to methane oxidation: Insight into oxidation and spin states from high resolution 1s core hole X-ray spectroscopy

2012 ◽  
Vol 113-114 ◽  
pp. 43-51 ◽  
Author(s):  
Evgeny V. Kudrik ◽  
Olga Safonova ◽  
Pieter Glatzel ◽  
Janine C. Swarbrick ◽  
Leonardo X. Alvarez ◽  
...  
Keyword(s):  
High Resolution ◽  
Methane Oxidation ◽  
Spin States ◽  
Core Hole ◽  
X Ray ◽  
Insight Into

Developments in Scanning Auger Microscopy

1978 ◽  
Vol 36 (3) ◽  
pp. 280-291
Author(s):  
J.A. Venables ◽  
A.P. Janssen
Keyword(s):  
Auger Electron ◽  
Light Element ◽  
Mean Free Path ◽  
Element Analysis ◽  
Auger Electrons ◽  
X Ray ◽  
Atomic Relaxation ◽  
Auger Microscopy ◽  
Energy Processes ◽  
Inelastic Mean Free Path

In the last decade, Auger Electron Spectroscopy (AES) has become a standard tool of surface physics and chemistry. Under electron bombardment, atoms emit Auger electrons having characteristic energies, so that the atomic species present can be identified after the manner of X-ray spectroscopy. AES is complementary to X-ray spectroscopy in several ways. First, it is much more surface sensitive, since the inelastic mean free path for Auger electrons, whose energies are typically in the range 50 - 1500 eV, is ~ lnm. Second, atomic relaxation following the primary ionization results in either an X-ray or an Auger electron. Auger emission is dominant for low energy processes, so that AES is relatively more favourable for light element analysis than X-ray spectroscopy.

Plasmon Satellites in Auger Spectra

1974 ◽  
Vol 52 (7) ◽  
pp. 624-638 ◽  
Author(s):  
T. McMullen ◽  
B. Bergersen
Keyword(s):  
Perturbation Expansion ◽  
Core Hole ◽  
Auger Electrons ◽  
Fast Electrons ◽  
X Ray ◽  
Soluble Model ◽  
Bulk Plasmon ◽  
Initial Excitation ◽  
Auger Spectra ◽  
Limiting Case

A theory of Auger spectra in light metals, in which a nonequilibrium formalism is used to handle the aspects of the problem associated with energy loss of the fast electrons and decay of the excited core hole, is presented. The Auger electrons are assumed to reach the surface a time τ after the initial excitation. This time is determined by the decay characteristics of the initial core hole, the geometry, and the velocity of the Auger electrons. After τ, it is assumed that no interactions occur. Electron gas correlations are approximated by a bulk plasmon model. The initial excitation may be due to either X-ray or electron bombardment, although we concentrate on the former. Plasmon production by the primary ejected electrons and the suddenly created core hole is considered. The formalism is based on a perturbation expansion in the electron–plasmon interaction after extraction of the energy shifts, and this procedure is justified by comparison with a simple soluble model. It is applied to third-row (K; LL) Auger transitions. The plasmon gain satellite is compared to the main line, and the entire spectrum is computed in detail for the limiting case of a long lived core hole.

scholarly journals Femtosecond X-ray induced changes of the electronic and magnetic response of solids from electron redistribution

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Daniel J. Higley ◽  
Alex H. Reid ◽  
Zhao Chen ◽  
Loïc Le Guyader ◽  
Olav Hellwig ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Valence State ◽  
Spin Dynamics ◽  
Magnetic Response ◽  
Core Electron ◽  
X Ray ◽  
Valence Electrons ◽  
Induced Changes ◽  
X Ray Absorption ◽  
Insight Into

AbstractResonant X-ray absorption, where an X-ray photon excites a core electron into an unoccupied valence state, is an essential process in many standard X-ray spectroscopies. With increasing X-ray intensity, the X-ray absorption strength is expected to become nonlinear. Here, we report the onset of such a nonlinearity in the resonant X-ray absorption of magnetic Co/Pd multilayers near the Co L$${}_{3}$$3 edge. The nonlinearity is directly observed through the change of the absorption spectrum, which is modified in less than 40 fs within 2 eV of its threshold. This is interpreted as a redistribution of valence electrons near the Fermi level. For our magnetic sample this also involves mixing of majority and minority spins, due to sample demagnetization. Our findings reveal that nonlinear X-ray responses of materials may already occur at relatively low intensities, where the macroscopic sample is not destroyed, providing insight into ultrafast charge and spin dynamics.

scholarly journals Recoil-induced ultrafast molecular rotation probed by dynamical rotational Doppler effect

2019 ◽  
Vol 116 (11) ◽  
pp. 4877-4882 ◽  
Author(s):  
Denis Céolin ◽  
Ji-Cai Liu ◽  
Vinícius Vaz da Cruz ◽  
Hans Ågren ◽  
Loïc Journel ◽  
...  
Keyword(s):  
Delay Time ◽  
Doppler Effect ◽  
Auger Electron ◽  
Molecular Motion ◽  
General Point ◽  
Core Hole ◽  
Time Resolved ◽  
Pump Probe ◽  
X Ray ◽  
The Core

Observing and controlling molecular motion and in particular rotation are fundamental topics in physics and chemistry. To initiate ultrafast rotation, one needs a way to transfer a large angular momentum to the molecule. As a showcase, this was performed by hard X-ray C1s ionization of carbon monoxide accompanied by spinning up the molecule via the recoil “kick” of the emitted fast photoelectron. To visualize this molecular motion, we use the dynamical rotational Doppler effect and an X-ray “pump-probe” device offered by nature itself: the recoil-induced ultrafast rotation is probed by subsequent Auger electron emission. The time information in our experiment originates from the natural delay between the C1s photoionization initiating the rotation and the ejection of the Auger electron. From a more general point of view, time-resolved measurements can be performed in two ways: either to vary the “delay” time as in conventional time-resolved pump-probe spectroscopy and use the dynamics given by the system, or to keep constant delay time and manipulate the dynamics. Since in our experiment we cannot change the delay time given by the core-hole lifetime τ, we use the second option and control the rotational speed by changing the kinetic energy of the photoelectron. The recoil-induced rotational dynamics controlled in such a way is observed as a photon energy-dependent asymmetry of the Auger line shape, in full agreement with theory. This asymmetry is explained by a significant change of the molecular orientation during the core-hole lifetime, which is comparable with the rotational period.

scholarly journals Core-hole Electronic Structure Studies on Molecules using Synchrotron Radiation

1996 ◽  
Vol 49 (2) ◽  
pp. 457 ◽  
Author(s):  
Frank P Larkins
Keyword(s):  
Experimental Data ◽  
Electronic Structure ◽  
Synchrotron Radiation ◽  
Auger Electron ◽  
Core Hole ◽  
X Ray ◽  
Theoretical Investigations ◽  
Recent Developments ◽  
Simple Molecules

Some recent developments in the study of core-hole photoabsorption, photoionisation, X-ray emission, Auger electron decay and photofragmentation processes for molecules are discussed. The emphasis is on the interpretation of experimental data obtained from synchrotron radiation studies. New insights which are being obtained through theoretical investigations into the electronic and nuclear properties of excited and ionised states of simple molecules are reviewed.

scholarly journals Core hole processes in x-ray absorption and photoemission by resonant Auger-electron spectroscopy and first-principles theory

2020 ◽  
Vol 101 (24) ◽  
Author(s):  
J. C. Woicik ◽  
C. Weiland ◽  
A. K. Rumaiz ◽  
M. T. Brumbach ◽  
J. M. Ablett ◽  
...  
Keyword(s):  
Auger Electron Spectroscopy ◽  
First Principles ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Core Hole ◽  
X Ray ◽  
X Ray Absorption
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