First results from the high resolution XUV undulator beamline BW3 at HASYLAB

Larsson, Christer; Beutler, Andreas S.; Björneholm, Olle; Federmann, F.; Hahn, Ulrich; Rieck, Andreas; Verbin, S. Yu.; Möller, T.

doi:10.1016/0168-9002(94)91133-9

Cited by 95 publications

(27 citation statements)

References 21 publications

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“…The HEVMI spectrometer was located at a distance of 0.7 m away from the focus point of the monochromator, which results in an elliptical spot (162 m in the vertical by 410 m in the horizontal (FWHM)) at the interaction point with a divergence of about 0.1 mrad. Further details can be found elsewhere [18,25]. For detection a position-sensitive detector is used consisting of a single multichannel plate (MCP, RoentDek) and a phosphor screen (Proxivision) both of diameter = 80 mm.…”

Section: Methodsmentioning

confidence: 99%

A new design for imaging of fast energetic electrons

Skruszewicz

Passig

Przystawik

et al. 2014

International Journal of Mass Spectrometry

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a b s t r a c tWe report on an essentially improved version of the classical Eppink-Parker velocity map imaging spectrometer design (Rev. Sci. Instrum. 68, 3477 (1997)). By adding electrostatic lenses with an opposite polarity to the extraction system we succeeded in extending the range of detection of energetic particles up to the keV regime at moderate (<20 kV) extraction voltage conditions. Simulations show that the electrostatic lens system acts in analogy to an achromatic lens in optics and leads to a reduction in the chromatic energy aberration. For comparison to other setups a transmission parameter of the extraction system is defined denoting the maximum kinetic energies of particles which can be analyzed. Detector size and spectrometer length only enter via geometry, that is the straight trajectories in the subsequent field-free particle drift. With respect to Eppink-Parker the energy range has been extended by a factor of 2.5. Moreover, particle trajectory simulations demonstrate that the energy resolution can be improved by about 20%. To test the performance, photoemission studies have been conducted to resolve abovethreshold-ionization patterns from Xe atoms exposed to intense ultrashort laser pulses as well as single photon ionization of Ne atoms using tunable synchrotron radiation with photon energies up to 600 eV.

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Section: Methodsmentioning

confidence: 99%

A new design for imaging of fast energetic electrons

Skruszewicz

Passig

Przystawik

et al. 2014

International Journal of Mass Spectrometry

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“…Our measurements were carried out at the undulator beamline BW3 of the Hamburger Synchrotron Radiation Laboratory HASYLAB at DESY [14]. Synchrotron radiation was monochromatized in a modified SX-700 plane grating monochromator with a usable energy range of approximately 20-2000 eV and a spectral resolution of 0.1 eV in the energy range applied here.…”

Section: Methodsmentioning

confidence: 99%

Partial photoionization cross sections of C60 and C70: A gas versus adsorbed phase comparison

et al. 2010

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We have performed high resolution measurements of the photoelectrons emitted from the valence shell of C70, in the gas and adsorbed phase on a metal surface, in order to derive branching ratios and the partial photoionization cross sections of the two highest occupied molecular orbitals, HOMO and HOMO-1. The comparison between the two phases and the adsorbed phase shows an interesting and unexpected difference that can be attributed to a small orbital shift in solid C70. Density Functional Theory calculations within the Local Density Approximation (LDA) show good agreement for both data sets and give a plausible explanation for the observed difference. IntroduktionThe discovery of the family of carbon molecules dubbed the 'fullerenes' [1] and the breakthrough in their synthesis [2] have stimulated an extensive research activity in this field. The best known among the fullerenes is the C60 molecule, which consists of 60 carbon atoms arranged on a nearly spherical shell with the highest possible symmetry, point group Ih. Recently, we have studied some of its particularly interesting properties by photoelectron spectroscopy [3]. Our results revealed strong oscillations in the partial photoionization cross sections of the two highest occupied molecular orbitals, HOMO and HOMO-1, reflecting the molecular geometry and symmetry of the electronic charge distribution.These oscillations, which were for the first time discovered in solid C60 and interpreted as a solid state effect [4,5], were later also observed for free C60 molecules [6]. Their interpretation was basically interpreted within a standing wave model of the photoelectron wave in a box like potential [7] being extended to a jellium like potential in a subsequent experimental and theoretical study [8]. It is the spherical like structure of the C60 molecule which gives rise to shell like distribution of the delocalized carbon valence electrons. However, one may look to the problem also from the view point of symmetry. The valence hole states HOMO and HOMO-1 have different symmetry gerade (g) and ungerade (u), a situation which may be compared to homonuclear diatomic molecules. Here the g and u states show also pronounced oscillations in their partial photoionization cross sections and even more pronounced oscillations in their photoelectron diffraction intensity behavior in the molecular frame. These oscillations which were predicted more than forty years ago by Cohen and Fano [9] have been experimentally corroborated since the last ten years only [10,11]. Regarding photoionization this was even more recently [12]. The showcase example exhib-

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“…The BW3 beamline at DORIS III has an energy range between 20 and 1500 eV, with the photon flux below 1000 eV being on the order of 10 12 photons/0.1% bandwith [13][14][15]. Higher harmonics are present in the percent level below 50 eV, preventing the beamline's use below this energy for a straight forward calibration of the I-TOF.…”

Section: The Beamlinementioning

confidence: 99%

Using I-TOF spectrometry to measure photon energies at FELs

Juranić¹,

Martins²,

Viefhaus³

et al. 2009

J. Inst.

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Due to the stochastic nature of the Self Amplifying Spontaneous Emission (SASE) process and the resulting pulse-to-pulse fluctuations of the Free Electron Laser (FEL) photon energies, experimenters working with FELs need to get real-time feedback about the photon properties for their experiments. Investigations of narrow atomic or molecular resonances, phase transitions, or any other kind of effect heavily dependent on photon energy would need to know the precise FEL photon energy for each individual photon bunch. Furthermore, any spectrometer developed to deliver the information of these properties should not significantly interfere or degrade the FEL beam. Therefore, the group at the Free Electron Laser in Hamburg (FLASH) has developed an online photoionization spectrometer that uses ion time of flight (I-TOF) measurement methods on noble gases to measure the photon energy of each pulse. This paper presents the first test results for the viability of this online photoionization spectrometer (OPS).

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First results from the high resolution XUV undulator beamline BW3 at HASYLAB

Cited by 95 publications

References 21 publications

A new design for imaging of fast energetic electrons

A new design for imaging of fast energetic electrons

Partial photoionization cross sections of C60 and C70: A gas versus adsorbed phase comparison

Using I-TOF spectrometry to measure photon energies at FELs

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