Circular Dichroism in Cu Resonant Auger Electron Diffraction

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.

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

Australian Journal of Physics ◽

10.1071/ph860633 ◽

1986 ◽

Vol 39 (5) ◽

pp. 633 ◽

Cited By ~ 35

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.

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Patterns and paschen-back analogue in the stark-effect for neon

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1929.0056 ◽

1929 ◽

Vol 123 (791) ◽

pp. 80-103 ◽

Cited By ~ 8

Keyword(s):

Quantum Number ◽

Stark Effect ◽

Selection Rule ◽

Theoretical Calculations ◽

Zeeman Effect ◽

Final States ◽

Outer Electron ◽

Initial State ◽

Final State ◽

Left Handed

While the Stark-effect has not been studied so extensively as the Zeeman-effect, either in the experiments or in their interpretations, many of the more prominent features have been observed and have received adequate explanation on the quantum theory. Among these may be mentioned the patterns characteristic of the different series in the singlet system of parhelium. The variety of observed patterns in the Stark-effect, as contrasted with the normal Zeeman-effect found for all series of this system, arises from a differential action of the external electric field on the initial and final states, and a breaking down of the usual selection rule for the azimuthal quantum number. Some simplification is brought about, however, by the fact that only the absolute value of the quantum number m has any meaning in the interpretation of these photographs, since the action of the field is the same for right or left-handed motion of the outer electron in its orbit. This results in asymmetrical patterns for all the lines. The number of components observed in the patterns of individual lines of parhelium is in accord with the theoretical view that the vector j (here equal to l ) is resolved along the direction of the applied field to give the integral m values ranging from - j to + j , and that the usual selection rule holds for m . The displacements and intensities are in excellent agreement with the theoretical calculations based on the perturbation theory of quantum mechanics. The spacing of the sub-levels identified by ± m in the initial state is decidedly irregular in the Stark-effect as compared with the normal Zeeman-effect, where the displacements are proportional to m . The Zeeman order of the levels is usually reversed, in fact, and the spacing is uneven. Displacements in the final state are theoretically very small, and have not been observed with certainty. In the Stark-effect for orthohelium (triplet system) the same group of patterns was observed. An explanation of these observations, which is slightly less satisfactory than that obtained with parhelium, has been made by similar methods, neglecting the electron spin. Thus the m values were again given ranges determined in each case by the l of the outer electron, and not by the j for the whole atom. Most of the plates failed to reveal any of the fine structure of the normal orthohelium spectrum.

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

Modern Physics Letters B ◽

10.1142/s0217984913300123 ◽

2013 ◽

Vol 27 (16) ◽

pp. 1330012 ◽

Cited By ~ 13

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.

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

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1807812116 ◽

2019 ◽

Vol 116 (11) ◽

pp. 4877-4882 ◽

Cited By ~ 5

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.

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Auger Electron and Photoelectron Diffraction in Magnetic Thin Films

MRS Proceedings ◽

10.1557/proc-313-659 ◽

1993 ◽

Vol 313 ◽

Cited By ~ 11

Author(s):

Y.U. Idzerda ◽

D.E. Ramaker

Keyword(s):

Quantum Number ◽

Auger Electron ◽

Spherical Wave ◽

Magnetic Thin Films ◽

Single Scattering ◽

Final State ◽

Photoelectron Diffraction ◽

Angular Momentum Quantum Number ◽

Cluster Calculations

ABSTRACTThe role of the final-state character of the emitted electron in Auger electron diffraction (AED) and x-ray photoelectron diffraction (XPD) is examined with respect to magnetic materials. Single scattering cluster calculations with the inclusion of the spherical wave character and the final-state character of the emitted electron (both angular momentum quantum number and magnetic quantum number) show that selective emission from different M-levels, generated by a non-statistical distribution of initial M-levels or by an M-selective excitation process, results in distinctly different emission patterns.

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The fluorescence spectrum of NO2: rotationally-forbidden bands and their interpretation

Canadian Journal of Physics ◽

10.1139/p77-185 ◽

1977 ◽

Vol 55 (16) ◽

pp. 1453-1461 ◽

Cited By ~ 21

Author(s):

H. D. Bist ◽

J. C. D. Brand ◽

A. R. Hoy

Keyword(s):

Excited State ◽

Electronic State ◽

Fluorescence Spectrum ◽

Quantum Number ◽

Ground State ◽

Vibronic Coupling ◽

Gas Pressure ◽

Initial State ◽

Final State ◽

Vibrational Levels

Fluorescence of NO2 excited near 5000 Å at low gas pressure is predominantly 'parallel' in type, i.e., the values of the quantum number K in the initial state of the excitation, the intermediate (excited) state, and the final state(s)of the emission are all equal, Ki = K′ = Kf. However, a considerable number of the weaker fluorescence bands do not conform to this pattern; instead, they correspond to even-parity differences between the initial and final value of K, |Kf − Ki| = 2, 4, or 6, indicating that K (though not N) is a poor quantum number in the upper electronic state of the excitation–emission sequence. The observations are analyzed in terms of a mechanism in which the vibronic coupling between the 2B2 excited state and high vibrational levels of the ground state creates conditions where the asymmetry of the 2B2 basis state produces unexpectedly large couplings between hybrid states of the same parity in K.

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SPIN EXPANSION FOR HEAD-ON COLLISION OF TWO BLACK HOLES

International Journal of Modern Physics D ◽

10.1142/s0218271811018639 ◽

2011 ◽

Vol 20 (01) ◽

pp. 43-57 ◽

Cited By ~ 4

Author(s):

ZHOUJIAN CAO ◽

CHENZHOU LIU

Keyword(s):

Black Holes ◽

Black Hole ◽

Angular Momentum ◽

Orbital Angular Momentum ◽

New Method ◽

Initial State ◽

Final State ◽

The Third ◽

Binary Black Hole ◽

Expansion Technique

The spin expansion technique proposed in [L. Boyel, M. Kesden and S. Nissanke, Phys. Rev. Lett.100 (2008) 151101] is very powerful to analyze the relation between the initial state of binary black hole and the final state of the merged black hole. But this technique needs orbital angular momentum to determine the third direction of a triad. Without this triad we cannot get the decomposed components of the involved quantities, and the spin expansion breaks down. The head-on collision of two black holes, whose orbital angular momentum vanishes, falls into this case. In this paper we propose a new method to construct a triad for spin expansion technique. With this new method, we get the same set of equations as in the above-mentioned paper. Furthermore, we use numerical simulations to illustrate the validity of our new method for the head-on collision of two black holes.

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Parallel and antiparallel angular momentum transfer of circularly polarized light to photoelectrons and Auger electrons at the Ni L3 absorption threshold

Physical Review B ◽

10.1103/physrevb.97.035424 ◽

2018 ◽

Vol 97 (3) ◽

Cited By ~ 1

Author(s):

Fumihiko Matsui ◽

Hiroshi Ota ◽

Kenji Sugita ◽

Matthias Muntwiler ◽

Roland Stania ◽

...

Keyword(s):

Angular Momentum ◽

Momentum Transfer ◽

Polarized Light ◽

Auger Electrons ◽

Circularly Polarized Light ◽

Circularly Polarized ◽

Angular Momentum Transfer

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Dual subtractions

Journal of High Energy Physics ◽

10.1007/jhep06(2021)089 ◽

2021 ◽

Vol 2021 (6) ◽

Author(s):

Renato Maria Prisco ◽

Francesco Tramontano

Keyword(s):

Field Theory ◽

Quantum Field ◽

Matrix Elements ◽

Leading Order ◽

Initial State ◽

Final State ◽

Dual Representation ◽

Subtraction Scheme ◽

Theoretical Predictions ◽

Perturbative Quantum

Abstract We propose a novel local subtraction scheme for the computation of Next-to-Leading Order contributions to theoretical predictions for scattering processes in perturbative Quantum Field Theory. With respect to well known schemes proposed since many years that build upon the analysis of the real radiation matrix elements, our construction starts from the loop diagrams and exploits their dual representation. Our scheme implements exact phase space factorization, handles final state as well as initial state singularities and is suitable for both massless and massive particles.

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