An efficient low-energy electron-spin-polarization analyzer

Erbudak M, Müller N. An efficient low-energy electron-spin-polarization analyzer. Applied physics letters. 1981;38(7):575-577.The spin-orbit coupling in the scattering of electrons at the surface of a gold crystal induces a spin-dependent absorption of electrons. A huge spin dependence of the absorbed current is observed, which promises the realization of an electron-spin-polarization analyzer with an efficiency of over 10 -2. Applied Physics Letters is copyrighted by The American Institute of Physics

Role of the Exposed Pt Active Sites and BaO2 Formation in Nox Storage Reduction Systems: A Model Catalyst Study on BaOx/Pt(111)

Cataloged from PDF version of article.BaOx(0.5 MLE - 10 MLE)/Pt(111) (MLE: monolayer equivalent) surfaces were synthesized as model NOx storage reduction (NSR) catalysts. Chemical structure, surface morphology, and the nature of the adsorbed species on BaOx/Pt(111) surfaces were studied via X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD), and low-energy electron diffraction (LEED). For theta(BaOx) = 2.5 MLE) were found to be amorphous. Extensive NO2 adsorption on BaOx(10 MLE)/Pt(111) yields predominantly nitrate species that decompose at higher temperatures through the formation of nitrites. Nitrate decomposition occurs on BaOx(10 MLE)/Pt(111) in two successive steps: (1) NO(g) evolution and BaO2 formation at 650 K and (2) NO(g) + O-2(g) evolution at 700 K. O-2(g) treatment of the BaOx(10 MLE)/Pt(111) surface at 873 K facilitates the BaO2 formation and results in the agglomeration of BaOx domains leading to the generation of exposed Pt(111) surface sites. BaO2 formed on BaOx(10 MLE)/Pt(111) is stable even after annealing at 1073 K, whereas on thinner films (theta(BaOx) = 2.5 MLE), BaO2 partially decomposes into BaOx indicating that small BaO2 clusters in close proximity of the exposed Pt(111) sites are prone to decomposition. Nitrate decomposition temperature decreases monotonically from 550 to 375 K with decreasing BaOx coverage within theta(BaOx) = 0.5 to 1.0 MLE. Nitrate decomposition occurs at a rather constant temperature range of 650-700 K for thicker BaOx overlayers (2.5 MLE < theta(BaOx) < 10 MLE). These two distinctly characteristic BaOx-coverage-dependent nitrate decomposition regimes are in very good agreement with the observation of the so-called "surface" and "bulk" barium nitrates previously reported for realistic NSR catalysts, clearly demonstrating the strong dependence of the nitrate thermal stability on the NOx storage domain size

Tracking tumor evolution via prostate-specific antigen: an individual post-operative study

<p>Abstract</p> <p>Background</p> <p>The progress of the prostate-specific antigen (PSA) level after radical prostatectomy is observed for a patient in order to extract information about the mode of tumor cell growth. Although PSA values are determined routinely to find the doubling time of the prostate marker, to our knowledge, this analysis is the first in the literature.</p> <p>Results</p> <p>The prostate tumor marker values were determined regularly after the surgery and plotted on a logarithmic scale against time. An initial rapid-growth mode changed to a slower power-law regime within two years of surgery. Our analysis associates this observation with a transition in the growth mode from unrestricted growth of dispersed cells to their clumping into macroscopic structures.</p> <p>Conclusions</p> <p>Such studies may help determine the appropriate time window for postoperative therapies in order to increase the life expectancy of the patient.</p

Determination of spin-polarisation for angle-resolved and energy-analysed secondary electrons

Erbudak M, Müller N. Determination of spin-polarisation for angle-resolved and energy-analysed secondary electrons. Journal of physics, E: Scientific instruments. 1984;17(11):951-953.An absorption detector for electron-spin polarisation is combined with a compact energy analyser. The energy analyser has an energy-matching and transport lens at its entrance. This combination is used to measure the intensity, the intensity-asymmetry due to the modulation of primary beam polarisation, and the spin-polarisation of secondary electrons. Results are shown for secondary electrons from a Au (110) surface

Search for broken symmetry in the Au(110) surface: dedicated to Professor Dr. H. Jagodzinski on his 65th birthday

Müller N, Erbudak M, Wolf D. Search for broken symmetry in the Au(110) surface: dedicated to Professor Dr. H. Jagodzinski on his 65th birthday. Solid State Communications. 1981;39(11):1247-1249.Spin polarized LEED results are presented which confirm predicted symmetry induced properties. Contrary to recent claims, the results do not provide any evidence for a broken bulk derived symmetry in the Au(110) surface

Transversal polarization vector in LEED from Au(110)

Erbudak M, Ravano G, Müller N. Transversal polarization vector in LEED from Au(110). Physics Letters, A. 1982;90(1-2):62-64.We present the first measurements of both transversal components of the spin polarization vector of electrons diffracted from a Au (110) surface, obtained with an absorption detector. The results clearly demonstrate multiple scattering effects