Photoemission Spectroscopy (X-ray = XPS, Ultraviolet = UPS), Auger Electron Spectroscopy (AES) and Low Energy Electron Spectroscopy (LEED) - Parasol
The Parasol offers the possibility to prepare and investigate the sample surface by multiple surface probe techniques. The system is equipped with a hemisphere analyzer (SPECS, PHOIBOS 100), the overall energy resolution is lower than 0.3 eV. The analyzer is capable of analyzing the (kinetic) energies of the sample emitted electrons, which are excited by X-rays, Ultraviolet (UV), and electron beam. The system is also equipped by a Low Energy Electron Diffraction (LEED) to investigate the surface ordering. The structure of the deposited metal or gas molecular can be monitored by a low-beam current LEED. The system is operating under ultra-high vacuum (UHV) condition to reduce the surface contamination. The system contains four chambers, load-lock, molecule, preparation, and analyzing chamber.
The load-lock chamber is only for transferring the sample from atmosphere to UHV, without breaking the vacuum of the main chambers.
The preparation chamber contains a 4-axis manipulator which can be used for transferring the sample to different positions. In order to remove the surface contamination, several sputtering and annealing cycles are applied. The sputter gun can produce energetic ions to bombard the surface to remove the surface contamination. The sample can be cooled down to 40 K with liquid helium (LHe) or 90 K with liquid nitrogen (LN2), and, while cooling with LN2, the sample can stay at 1200 K for 30 min with the manipulator remaining lower than 200 K. The chamber is also equipped with a e-beam evaporator, for depositing metal onto the sample surface.
The molecule chamber has a dosing tube which is mounted on a manipulator, in order to dose molecules in close proximity to the surface. A Quadrupole Mass Spectrometer (QMS) is mounted to check the cleanliness of the molecule.
The analysis chamber is equipped with a hemispherical analyzer to analyze the kinetic energy of emitted electrons. There are several sources to generate surface emitted electrons: X-ray source (Mg and Al K-α) for XPS, UV-lamp (He-I and He-II) for UPS, and an electron gun (0-5 keV) for AES. In order to study the electronic configuration of insulators, a low-energy flood gun is installed to remove the charging effect. Since all measurements are performed on the manipulator, samples can be measured at low temperature down to 40 K by LHe and 90 K by LN2.