Search results for "Photoelectron spectroscopy"
showing 10 items of 439 documents
Orientation and substrate interaction of adsorbed CO and NO molecules probed by circular dichroism in the angular distribution of photoelectrons.
1994
The sensitivity and utility of circular dichroism in the angular distribution of photoelectrons (CDAD) as a probe of molecular orientation is demonstrated for adsorbed CO and NO molecules. A comparison between measured CDAD spectra and calculated values for spatially oriented CO and NiCO clearly confirms the well-known perpendicular adsorption for CO on Ni(100), whereas for CO adsorbed on Fe(100) a tilted adsorption geometry was found. For NO/Ni(100) and for NO on the oxygen-preadsorbed Ni(100) surface, an average tilt angle of α=40±10° was observed. In the case of the oxygen-preadsorbed Ni(100) surface, a higher fraction of NO molecules was found to be in a tilted orientation than on the c…
Exchange coupling in the correlated electronic states of amorphous GdFe films
2013
The bulk sensitivity of hard x-ray photoelectron spectroscopy in combination with circularly polarized radiation of the P09 beamline at PETRA III enables the investigation of the magnetic properties of capped films. We have determined the temperature dependence of the magnetic circular dichroism in the Fe 2$p$ and in the Gd 3$d$ states in amorphous GdFe films. The magnetic dichroism reflects the stronger temperature dependence of Gd moments compared to Fe moments in agreement with mean-field models. We resolved the exchange split Gd 3${d}_{5/2}$ substates and found a significant temperature dependence of the splitting which is attributed to a temperature dependent part of the exchange energ…
Dichroism in VUV photoemission from the (0001)-surfaces of ultrathin Gd and Nd films on W(110)
1997
Abstract Ultrathin layers of Gd and Nd epitaxially grown on W(110) have been investigated using linearly and circularly polarised light at the 6.5 m NIM beamline at the BESSY storage ring in Berlin. The high quality of the films was monitored by the sharp and dispersionless surface state just below the Fermi energy. The CDAD (circular dichroism in the angular distribution of photoelectrons) measurements showed strong effects in the surface states as well as in the valence bands. The LMDAD (linear magnetic dichroism in…) from Gd(0001) showed a small, but significant splitting of the surface state. This splitting can be reproduced by numerical one-step calculations based on spin-dependent sur…
Chemical-state analyses of Ni, Zn, and W ions in NiWO$_4$-ZnWO$_4$ solid solutions by X-ray photoelectron spectroscopy
2022
The chemical states of Ni, Zn, and W in microcrystalline NiWO$_4$-ZnWO$_4$ solid solutions were studied by X-ray photoelectron spectroscopy. The recorded spectra of the Ni 2p, Zn 2p, and W 4f photoelectron lines and Ni L$_2$M$_{23}$M$_{45}$, Zn L$_3$M$_{45}$M$_{45}$, and W N$_4$N$_{67}$N$_{7}$ Auger-transition lines show pronounced changes with increasing Zn concentration. The positions of the resolved photoelectron and Auger-transition lines were combined to construct so-called chemical-state plots (Wagner or Auger-parameter plots) for metal ions in solid solutions. With increasing Zn concentration, the Auger parameter increases for Ni and decreases for W, thus evidencing a lowering and an…
Clean and ordered surfaces of CeNi 2 Ge 2 layers on W(110)
1997
Investigations of the geometric and electronic properties of ternary Ce-based heavy fermion systems CeT2X2 (T : Ni,Pd,Rh; X : Ge,Si) were carried out by means of electron spectroscopic methods. The main problem for these surface-sensitive techniques is the preparation of well-ordered and atomically clean surfaces. The ternary substance CeNi2Ge2 was grown on a W(110) substrate by MBE with subsequent annealing. A nearly layer-by-layer growth mode was detected using MEED. The annealed layers are ordered, but show small Ni2Ge crystalline islands. The composition was characterised by means of AES in dependence of the substrate as well as the annealing temperature. Electronic properties are inves…
Photoelectron spectroscopy of thin discontinuous metal films deposited onto a sapphire substrate
1995
Abstract The charging of small metallic clusters forming discontinuous gold and gallium films, condensed in vacuum onto an insulating substrate (sapphire), was experimentally studied by the method of ultraviolet photoelectron spectroscopy (UPS) for a photon energy of 5.4 eV. It seems that the charging is due to electron emission as well as to electron transfer from metal islands to the empty electron states in the metal-insulator interface.
Valence band photoemission from thin iron films - A comparison of experimental and theoretical results
1998
Abstract In this contribution, we report on photoemission data from thin iron films on W(110) that have been carried out by means of spin-resolved photoelectron spectroscopy as well as Magnetic Circular Dichroism in valence band photoemission at the storage ring BESSY. These techniques give complementary information on the electronic and magnetic properties, such as exchange and spin–orbit splitting. We compare our experimental data to new photoemission calculations, which have been obtained in the framework of a fully relativistic one-step theory for ferromagnetic materials.
Spin-polarization effects for electrons passing through thin iron and cobalt films
1993
Abstract Spin-dependent effects of the inelastic mean free path (IMFP) are evident for low-energy electrons passing through magnetized ferromagnetic films caused by a different attenuation within the layer. Values of IMFP for both spin components were determined for ultrathin iron and cobalt layers on W(1 1 0) by means of spin-resolving photoelectron spectroscopy.
Comprehensive Study of Poly(2,3,5,6-tetrafluoroaniline): From Electrosynthesis to Heterojunctions and Ammonia Sensing.
2018
In this work, we report for the first time on a comprehensive study of poly(2,3,5,6-tetrafluoroaniline) (PTFANI). Contrary to the nonfluorinated polyaniline (PANI) or its analogues bearing one fluorine atom, PTFANI is a poorly conductive material. We present a comprehensive study of the electrosynthesized PTFANI from its monomer in an acidic aqueous medium. PTFANI was fully characterized by a potential-pH diagram, spectroelectrochemistry, and electrochemical quartz crystal microbalance (EQCM) measurements, as well as by a morphological study. Combined with the X-ray photoelectron spectroscopy (XPS) analysis, it allowed us to understand the redox properties of this polymer compared to those …
Grafting and characterization of dodecylphosphonic acid on copper: Macro-tribological behavior and surface properties
2013
International audience; Thin film of n-dodecylphosphonic acid (DDPA) was prepared on a copper oxide substrate via a molecular self-assembly process. The composition, structure, organization, surface energy, morphology, and electrochemical behavior of the DDPA filmwere characterized bymeans of X-ray photoelectron spectroscopic analysis (XPS), polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), contact angle measurement v(CAM), microscopic observations, and electrochemistry. The friction behavior of the DDPA film adsorbed on copper oxide substrate sliding against a Si3N4 ball was examined on a linear reciprocating tribological tester. Worn surfaces of the DDPA film…