Workgroup Prof. Ziegler

Specs Phoibos X/U/I PES

Photoemission spectroscopy (PES) refers to the photoelectric effect (wikipedia). If a photon with sufficient energy hits an atom or molecule, it could be absorbed and triggers an electron of the atom or molecule. This collision preserves the total energy.

By changing the method and parameters, the surface's or solid's electronic constitution could be analyzed. From less then a monolayer up to 10 nm of a solid, information about surface adsorbates could be gathered.

PES System 1

Photoelectronspectroscopy ...

Investigation Methods for Analysis
- X-ray photoelectron spectroscopy (XPS, ESCA)
- UV
- Inverse photoelectron
- Electron Energy Loss Sepctroscopy (EELS)
- Angle Resolved photoelectron spectroscopy with x-ray or UV light (ARPES)
- Solar spectra light source

Chamber specifications built by PREVAC / OMNIVAC
- pressure < 10^-10 mbar
- samples could be heated up to 250°C and cooled down by LN2 to -50°C
- sample shape could be individual, sample size from <10 mm x 10 mm

Specs Phoibus 150 Series Spectrometer
- 180° Hemispherical Energy Analyzer (HSA 3500 Series)
- Capacitor Radios = 150 mm
- Detection: multi channel detector (MCD) with 9 channels
- Operation modes:
 - fixed retarding ratio (FRR)
 - fixed analyzer transmission (FAT)
- spot size diameter from 0,1 mm up to 20 mm
- angular resolution up to +/- 1° for ARPES


Specs UV Source UVS 35
- discharge lamp with quarz capillary
- high intensity photocurrent between 15 nA and 40 nA
- high flux > 8 x 10^15 photons / sr x s
- small beam divergence < +/- 1°
- differential pumping
- operation with He I / II, Ne II, Ar II


X-ray source RQ 20/30 C Typ Henkel
- Leybold high voltage supply (HVS), operation at 12 kV
- Leybold emission regulation, operation at 10 mA
- Leybold cooling water isolation box
- Kathode material Aluminium (Al, xxx eV) or Magnesium (Mg, xx eV)


Kimball Physics Electron Gun ELG-2 / EGPS-2
- Beam Energy Range 5 eV to 1000 eV, spread +/- 0,4 eV
- Beam Current 1 nA to 10 µA
- Beam Uniformity Gaussian
- Barium Cathode (heatable)
- Spot Size 0,5 mm to 5 mm

 

Photodetector, homebuild (Dr. Jens Wüsten)
- Detection of monochromatic photons
- Energy Bandpass between 9,8 eV (SrF2 Window) and 9,2 eV (NaCl Photocathode)
- Channeltron with Keithley 6487 Picoammeter / Voltage Source
- Software: Keysight VEE


LOT Oriel Instruments mercury lamp
- Model 66900
- Power 50 W to 500 W

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