Theoretical studies in photoelectron spectroscopy. Molecular optical activity in the region of continuous absorption and its characterization by the angular distribution of photoelectrons

Ritchie, Burke

doi:10.1103/physreva.12.567

Cited by 85 publications

(31 citation statements)

References 16 publications

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“…As a consequence, this CD in the differential photoionization cross section is expected to be significantly larger than the CD in photoabsorption or the CD of the total (angleintegrated) photoelectron yield. For the case of oriented molecules, similar polarization dependencies of differential photoionization cross sections were discussed theoretically by Ritchie [7], Cherepkov and Kuznetsov [8], and Dubs et al [9] and have been found in a number of experimental investigations [10][11][12][13][14]. However, for unoriented nonchiral targets, these effects usually cancel out due to averaging by integration over all possible directions of the molecular axes.…”

Section: Introductionsupporting

confidence: 63%

Circular dichroism in valence photoelectron spectroscopy of free unoriented chiral molecules: Camphor and bromocamphor

et al. 2004

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The circular dichroism in the photoelectron angular distribution was investigated for valence photoionization of randomly oriented pure enantiomers of camphor and bromocamphor molecules using circularly polarized light in the vacuum ultraviolet. The forward-backward electron emission spectra were recorded simultaneously with two spectrometers at several opposite angles relative to the propagation direction of the photon beam and compared for each of the two substances. Measurements were also carried out for reversed light helicity and opposite molecular handedness. For the left-and right-handed enantiomers of both molecules we observed asymmetries of comparable magnitude up to several percent. The measured asymmetry parameters vary strongly for different orbital binding energies and also for the selected photon energies in the valence region. The results for both molecules are compared. They suggest a strong influence of the final states on the asymmetry, depending on the chiral geometry of the molecular electronic structure, as well as a significant dependence on the initial states involved. They also confirm theoretical predictions describing the effect in pure electric-dipole approximation.

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Section: Introductionsupporting

confidence: 63%

Circular dichroism in valence photoelectron spectroscopy of free unoriented chiral molecules: Camphor and bromocamphor

et al. 2004

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“…Yet this is a desirable goal since it would provide an atom-specific means of detecting the presence of chiral centers in adsorbed molecules, either in an adsorbate that is chiral already, or in which such a feature is produced by adsorption-induced deformation. Theoretical treatments have predicted that spatially oriented chiral molecules, such as may be present in adsorbed layers, should show circular dichroism (CD), i.e., a dependence of intensity on helicity of the light, in the angular distribution of photoelectrons [8]. Even in randomly oriented chiral molecules in the gas phase, such an effect was predicted and recently experimentally verified both in core-level and valence-level photoemission [9].…”

mentioning

confidence: 99%

Atom-Specific Identification of Adsorbed Chiral Molecules by Photoemission

et al. 2005

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The study of chiral adsorbed molecules is important for an analysis of enantioselectivity in heterogeneous catalysis. Here we show that such molecules can be identified through circular dichroism in corelevel photoemission arising from the chiral carbon atoms in stereoisomers of 2,3-butanediol molecules adsorbed on Si(100), using circularly polarized x rays. The asymmetry in the carbon 1s intensity excited by right and left circularly polarized light is readily observed, and changes sign with the helicity of the radiation or handedness of the enantiomers; it is absent in the achiral form of the molecule. This observation demonstrates the possibility of determining molecular chirality in the adsorbed phase.

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“…This is expected since for magnetic circular dichroism, spin orbit (SO) coupling is necessary, but here such coupling is neglected in va- lence and continuum states. Circular dichroism in the angular distribution (CDAD) [53][54][55][56][57][58][59][60] effects are also absent, as the geometrical set up is not chiral. The RPES signal, however, shows a large dichroism, which is maximum for the strongest enhancement of the signal and of opposite sign for the two spin channels.…”

Section: Resultsmentioning

confidence: 99%

Real-space Green's function approach to angle-resolved resonant photoemission: Spin polarization and circular dichroism in itinerant magnets

Pieve

Krüger

2013

Phys. Rev. B

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A first principles approach, based on the real space multiple scattering Green's function method, is presented for spin-and angle-resolved resonant photoemission from magnetic surfaces. It is applied to the Fe(010) valence band photoemission excited with circularly polarized X-rays around the Fe L3 absorption edge. When the photon energy is swept through the Fe 2p − 3d resonance, the valence band spectra are strongly modified in terms of absolute and relative peak intensities, degree of spin-polarization and light polarization dependence. New peaks in the spin-polarized spectra are identified as spin-flip transitions induced by exchange decay of spin-mixed core-holes. By comparison with single atom and band structure data, it is shown that both intra-atomic and multiple scattering effects strongly influence the spectra. We show how the different features linked to states of different orbital symmetry in the d band are differently enhanced by the resonant effect. The appearance and origin of circular dichroism and spin polarization are analyzed for different geometries of light incidence and electron emission direction, providing guidelines for future experiments.PACS numbers: 78.20. Bh, 78.20.Ls, In the last decade, magnetic circular dichroism (MCD) and spin polarization studies in resonant inelastic X-ray scattering (RIXS) and resonant photoemission (RPES) have acquired great importance in the study of magnetic and correlated materials. Such spectroscopies probe respectively the radiative and non radiative autoionization decay of a core hole, and the signal can be strongly enhanced with respect to the non resonant mode. The element and orbital selectivity of core level resonant spectroscopies allows to access higher order multipoles which are left unexplored by MCD in X-ray absorption (XAS) [1][2][3][4][5][6], to distinguish and enhance specific electronic excitations and satellites [7,8], collective magnetic excitations [9], ultrafast and charge transfer dynamics [10][11][12] and to detect quadrupolar transitions towards localized empty states [13,14]. In particular, RPES has recently been applied to several correlated materials [15][16][17][18][19] and full two dimensional angular scans of resonantly emitted electrons in moderately correlated materials have also been carried out [20,21]. These works, together with earlier pioneering studies [22,23] on local magnetic properties in macroscopically non magnetic systems, demonstrate the importance of RPES and the need for an advancement in the theoretical description of this spectroscopy, which is the main aim of this work.RPES is in principle an autoionization channel of the * Electronic address: fabiana.dapieve@gmail.com more general process called resonant Auger decay. Depending on whether the core-excited electron participates or not in the Auger decay, the process is termed either participator or spectator channel. In the participator channel the one hole final state is degenerate with the one in direct valence band photoemission (PES, or ARPES if angle reso...

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Theoretical studies in photoelectron spectroscopy. Molecular optical activity in the region of continuous absorption and its characterization by the angular distribution of photoelectrons

Cited by 85 publications

References 16 publications

Circular dichroism in valence photoelectron spectroscopy of free unoriented chiral molecules: Camphor and bromocamphor

Circular dichroism in valence photoelectron spectroscopy of free unoriented chiral molecules: Camphor and bromocamphor

Atom-Specific Identification of Adsorbed Chiral Molecules by Photoemission

Real-space Green's function approach to angle-resolved resonant photoemission: Spin polarization and circular dichroism in itinerant magnets

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