Imaging SIMS for the investigation of substrate surfaces for CVD diamond deposition

The influence of substrate surface preparation on diamond nucleation is a major topic in the investigation of CVD-diamond deposition. The substrate, polishing material, its grain size, and the resulting surface roughness all influence diamond nucleation. Diamond can nucleate at scratches or residues of the polishing process which are providing nucleation sites. In this paper the surface of molybdenum and substrates polished with SiC and diamond powder was studied by imaging (2- and 3-dimensional) secondary ion mass spectrometry. The distribution and grain size of polishing residues (SiC, diamond) were determined and the reaction of diamond with the substrate during heating to deposition temperature was investigated. In this case a laterally inhomogeneous system of carbon containing species had to be characterized. Therefore compound-specific secondary ion mass spectrometry had to be performed. The results suggested that diamond residues on molybdenum substrates are partly dissolved during the heat treatment. The measurements indicate that a fraction of the diamond residues is still present after heat treatment and can provide nucleation sites for diamond deposition.     

The Cu valence in the highT c superconductors and in monovalent,divalent and trivalent copper oxides determined from XPS core level spectroscopy

A number of theoretical models have been developed to explain the unexpected high temperature superconductivity in La-Me-Cu-oxides (Me=Ba, Sr) and Y-Ba-Cu-oxides. Some of these models invoke charge fluctuations on the copper ions in the superconductors between a 2⁺ and a 3⁺ state. In order to test these possibilities we have measured the Cu–2p _3/2-core level spectra of NaCuO₂ in which the copper ion is in a 3⁺ state and compared it with the core line position in pure CuO and to superconducting oxides. The data strongly suggest, that there is, if any very little Cu³⁺ in the superconducting compounds present. However, we notice, that in comparison to trivalent and monovalent copper oxides the Cu–2p _3/2 line in CuO and the superconducting oxides is unexpectedly broad. The cause of this large linewidths remains so far unexplained.     

Molecular genetic diagnosis of de novo and recurrent bladder cancer

Bladder cancer, the second most common urological tumor, is usually diagnosed by endoscopy and biopsy of the lower urinary tract. However, this procedure is expensive, can cause discomfort to the patient and is a source of infection. Commercially available diagnostic systems measure protein byproducts of bladder carcinoma in voided urine; their sensitivity is only between 60-80%. Polymerase chain reaction (PCR)-based microsatellite analysis of the urine sediment (MAUS) is a noninvasive, inexpensive and easily performed analytical method which was introduced in the de novo diagnosis and follow-up of bladder cancer. By utilizing the PCR with 20 polymorphic microsatellite markers on different chromosomes and separating PCR products by electrophoresis on 7% denaturing polyacrylamide-formamide-urea slab gels, a 91% diagnostic sensitivity could be achieved. In order to minimize costs and analysis time, the separation and detection of PCR products was carried out by capillary array electrophoresis and two-color fluorescent primer labeling/laser beam detection in another study. The accuracy of both methods was the same. In either detection system, MAUS is an accurate and promising tool in the noninvasive diagnosis of bladder cancer.     

Electrostatic hyperfine interactions in Y(Fe,Al)2

Room temperature⁵⁷Fe Mössbauer and X-ray diffraction measurements are reported for Y(Fe_xAl^1–x)₂, 0.1x 0.9. For x0.65 broadened and on the Al-rich side structurized Bragg-peaks are observed. The asymmetry of the quadrupole split Mössbauer spectra depends on x. Whereas two different slopes are obtaind for the concentration dependence of the mean quadrupole splitting on the Al- and the Fe-rich side, the isomer shift exhibits a smooth dependence on x, which can be correlated to the change in volume caused by the Al substitution.