Development of a momentum microscope for time resolved band structure imaging

Krömker, B.; Escher, M.; Funnemann, D.; Hartung, D.; Engelhard, Hermann; Kirschner, J.

doi:10.1063/1.2918133

Cited by 141 publications

(111 citation statements)

References 23 publications

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“…Photon energies between 25-55 eV were utilized with left-handed circular (LCP) or righthanded circular (RCP) light polarization. The emitted photoelectrons were analysed with respect to their kinetic energy E kin and parallel momentum k || with the NanoESCA photoelectron emission microscope (PEEM, FOCUS/Omicron Nanotechnology) 28,[30][31][32] . For photoelectron momentum mapping, the focal plane of the PEEM can be imaged by an additional transfer lens behind the immersion lens objective.…”

Section: Methodsmentioning

confidence: 99%

Complete determination of molecular orbitals by measurement of phase symmetry and electron density

et al. 2014

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Several experimental methods allow measuring the spatial probability density of electrons in atoms, molecules and solids, that is, the absolute square of the respective single-particle wave function. But it is an intrinsic problem of the measurement process that the information about the phase is generally lost during the experiment. The symmetry of this phase, however, is a crucial parameter for the knowledge of the full orbital information in real space. Here, we report on a key experiment that demonstrates that the phase symmetry can be derived from a strictly experimental approach from the circular dichroism in the angular distribution of photoelectrons. In combination with the electron density derived from the same experiment, the full quantum mechanical wave function can thus be determined experimentally.

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Section: Methodsmentioning

confidence: 99%

Complete determination of molecular orbitals by measurement of phase symmetry and electron density

et al. 2014

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“…[27][28][29] The setup includes a nonmagnetic electrostatic photoelectron emission microscope and an aberration compensated double-pass hemispherical analyzer. This instrument is equipped with a transfer lens behind the immersion lens objective to map the angular distribution of the photoelectrons by imaging the focal plane.…”

Section: Methodsmentioning

confidence: 99%

Electronic and geometric structure of the PTCDA/Ag(110) interface probed by angle-resolved photoemission

et al. 2012

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The properties of molecular films are determined by the geometric structure of the first layers near the interface. These are in contact with the substrate and feel the effect of the interfacial bonding, which particularly, for metal substrates, can be substantial. For the model system 3,4,9,10-perylenetetracarboxylic dianhydride on Ag(110), the geometric structure of the first monolayer can be modified by preparation parameters. This leads to significant differences in the electronic structure of the first layer. Here, we show that, by combining angle-resolved photoelectron spectroscopy with low-energy electron diffraction, we cannot only determine the electronic structure of the interfacial layer and the unit cell of the adsorbate superstructure, but also the arrangement of the molecules in the unit cell. Moreover, in bilayer films, we can distinguish the first from the second layer and, thus, study the formation of the second layer and its influence on the buried interface.

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“…The kPEEM analysis was performed with a NanoESCA MkI spectromicroscope (ScientaOmicron) [14][15][16] in ultra-highvacuum conditions and at ambient temperature. An He I cold cathode lamp (hv = 21.2 eV) was employed as a laboratory vacuum-ultra-violet excitation source impinging the sample in an off-normal direction, namely, at an angle of 65°with respect to the sample normal.…”

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confidence: 99%

Free-standing electronic character of monolayerMoS2in van der Waals epitaxy

et al. 2016

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We have evaluated as-grown MoS 2 crystals, epitaxially grown on a monocrystalline sapphire by chemical vapor deposition (CVD), with direct electronic band-structure measurements by energy-filtered k-space photoelectron emission microscopy performed with a conventional laboratory vacuum ultraviolet He I light source under off-normal illumination. The valence states of the epitaxial MoS 2 were mapped in momentum space down to 7 eV below the Fermi level. Despite the high nucleation density within the imaged area, the CVD MoS 2 possesses an electronic structure similar to the free-standing monolayer MoS 2 single crystal, and it exhibits hole effective masses of 2.41 ± 0.05 m 0 , and 0.81 ± 0.05 m 0 , respectively, at and K high-symmetry points that are consistent with the van der Waals epitaxial growth mechanism. This demonstrates the excellent ability of the MoS 2 CVD on sapphire to yield a highly aligned growth of well-stitched grains through epitaxial registry with a strongly preferred crystallographic orientation.

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Development of a momentum microscope for time resolved band structure imaging

Cited by 141 publications

References 23 publications

Complete determination of molecular orbitals by measurement of phase symmetry and electron density

Complete determination of molecular orbitals by measurement of phase symmetry and electron density

Electronic and geometric structure of the PTCDA/Ag(110) interface probed by angle-resolved photoemission

Free-standing electronic character of monolayerMoS2in van der Waals epitaxy

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