Schottky type photodiodes as detectors in the VUV and soft x-ray range

Krumrey, Michael; Tegeler, E.; Barth, J.; Krisch, M.; Schäfers, F.; Wolf, R.

doi:10.1364/ao.27.004336

Cited by 105 publications

(23 citation statements)

References 19 publications

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“…The nomenclature of the fragments as well as the immonium ions are displayed. photon flux was monitored using a GaAsP-Schottky diode 31 located 23 cm behind the trap center. The protonated peptides were then exposed for about 0.1-1 s to the photon beam which was chopped by a mechanical shutter with a 14 mm aperture.…”

Section: Methodsmentioning

confidence: 99%

Photodissociation of protonated leucine-enkephalin in the VUV range of 8–40 eV

Bari

González-Magaña

Reitsma

et al. 2011

The Journal of Chemical Physics

116

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Until now, photodissociation studies on free complex protonated peptides were limited to the UV wavelength range accessible by intense lasers. We have studied photodissociation of gas-phase protonated leucine-enkephalin cations for vacuum ultraviolet (VUV) photons energies ranging from 8 to 40 eV. We report time-of-flight mass spectra of the photofragments and various photofragmentyields as a function of photon energy. For sub-ionization energies our results are in line with existing studies on UV photodissociation of leucine-enkephalin. For photon energies exceeding 10 eV we could identify a new dissociation scheme in which photoabsorption leads to a fast loss of the tyrosine side chain. This loss process leads to the formation of a residual peptide that is remarkably cold internally.

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Section: Methodsmentioning

confidence: 99%

Photodissociation of protonated leucine-enkephalin in the VUV range of 8–40 eV

Bari

González-Magaña

Reitsma

et al. 2011

The Journal of Chemical Physics

116

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“…Combined aliphatic-aromatic SAMs are less sensitive to electron bombardment, and X-ray beam damage is believed to be reduced [37]. For X-ray spectroscopy, we use a typical intensity of 4 × 10 13 photons/cm 2 s. The power is determined by a GaAsP-Schottky-diode [38,39] and the beam size by a phosphor mounted in the plane of the sample holder. For a typical XPS measurement and a 30 eV XAS scan, this corresponds to an exposure of 10 16 photons/cm 2 .…”

Section: X-ray Induced Beam Damagementioning

confidence: 99%

Azobenzene-functionalized alkanethiols in self-assembled monolayers on gold

Schmidt¹,

McNellis

Freyer³

et al. 2008

Appl. Phys. A

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Self-assembled monolayers (SAMs) of 4-trifluoromethyl-azobenzene-4 -methyleneoxy-alkanethiols (CF 3 -C 6 H 4 -N=N-C 6 H 4 -O-(CH 2 ) n -SH on (111)-oriented polycrystalline gold films on mica were examined by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The spectra are analyzed with the help of density-functional-theory calculations of the isolated molecule. Only one doublet is detected in the sulphur 2p spectra of the investigated SAMs, consistent with a thiolate bond of the molecule to the gold surface. The C 1s XP spectra and the corresponding XAS π * resonance exhibit a rich structure which is assigned to the carbon atoms in the different chemical surroundings. Comparing XPS binding energies of the azobenzene moiety and calculated initial-state shifts reveals comparable screening of all C 1s core holes. While the carbon 1s XPS binding energy lies below the π * -resonance excitation-energy, the reversed order is found comparing core ionization and neutral core excitation of the nitrogen 1s core-hole of the azo group. This surprising difference in core-hole binding energies is interpreted

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“…The measured drain currents were converted into photon flux using the quantum efficiency of clean gold, as cited in the literature [9]. Table I shows such data in the following way: in the first column is reported some selected photon energies for which the flux will be given; in the second column the mirror current reading is reported per 100 mA ring current; in the third column the Au efficiency values are shown [9]; in the fourth column the so-obtained flux values are given in units of photons͑͞s mm 2 ͒ 0.1% bw; in the last column an estimated error of the quoted flux is given. Such errors are quite large and have been extracted taking into account the variation of the ring current in time, the difficulties to estimate correctly the spot size on the sample, etc.…”

Section: B the Data Collectionmentioning

confidence: 99%

VUV photoemission studies of candidate Large Hadron Collider vacuum chamber materials

Cimino

Collins

Baglin

1999

Phys. Rev. ST Accel. Beams

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In the context of future accelerators and, in particular, the beam vacuum of the Large Hadron Collider (LHC), a 27 km circumference proton collider to be built at CERN, VUV synchrotron radiation (SR) has been used to study both qualitatively and quantitatively candidate vacuum chamber materials. Emphasis is given to show that angle and energy resolved photoemission is an extremely powerful tool to address important issues relevant to the LHC, such as the emission of electrons that contributes to the creation of an electron cloud which may cause serious beam instabilities and unmanageable heat loads on the cryogenic system. Here we present not only the measured photoelectron yields from the proposed materials, prepared on an industrial scale, but also the energy and in some cases the angular dependence of the emitted electrons when excited with either a white light (WL) spectrum, simulating that in the arcs of the LHC, or monochromatic light in the photon energy range of interest. The effects on the materials examined of WL irradiation and /or ion sputtering, simulating the SR and ion bombardment expected in the LHC, were investigated. The studied samples exhibited significant modifications, in terms of electron emission, when exposed to the WL spectrum from the BESSY Toroidal Grating Monochromator beam line. Moreover, annealing and ion bombardment also induce substantial changes to the surface thereby indicating that such surfaces would not have a constant electron emission during machine operation. Such characteristics may be an important issue to define the surface properties of the LHC vacuum chamber material and are presented in detail for the various samples analyzed. It should be noted that all the measurements presented here were recorded at room temperature, whereas the majority of the LHC vacuum system will be maintained at temperatures below 20 K. The results cannot therefore be directly applied to these sections of the machine until measurements at cryogenic temperatures, i.e., in the presence of cryosorbed gas layers, are obtained. However, these results are directly relevant to all the warm regions of the LHC vacuum system, such as the experimental vacuum chambers and warm element vacuum chambers in the insertion regions. [S1098-4402(99)

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Schottky type photodiodes as detectors in the VUV and soft x-ray range

Cited by 105 publications

References 19 publications

Photodissociation of protonated leucine-enkephalin in the VUV range of 8–40 eV

Photodissociation of protonated leucine-enkephalin in the VUV range of 8–40 eV

Azobenzene-functionalized alkanethiols in self-assembled monolayers on gold

VUV photoemission studies of candidate Large Hadron Collider vacuum chamber materials

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