Surface temperature of alkali halide is measured by a new extrapolation method. The sample surface is KBr(001), which is fixed on a sample heater by a flat spring in a vacuum chamber. Preparing small pieces of KBr other than the sample, copper-constantan thermocouples are inserted into three points A, B, and C, and temperatures, TA, TB and TC, are measured. Point A is between the heater and the KBr sample, B is between the KBr and a small piece of KBr on the sample, and C is between the KBr piece and tip of the flat spring. Temperatures TB and TC are measured for various thickness of KBr pieces without changing their cross-sectional area. The temperature difference between TB and TC is expected to decrease with decreasing thickness of the KBr piece, because both temperatures would approach to a unique value for negligibly thin piece. Extrapolating the temperatures TB and TC to zero thickness, we predict the surface temperature, TS. The temperatures TS are obtained for several heater temperatures, and temperature rise, ΔTS, by the heating are 70 to 80% with respect to those of temperatures TA. They are compared with TB extrapolated to zero thickness, TB0. Disagreement between TS and TB0 becomes obvious with increasing temperature. Thus some techniques for measurements are reviewed and a simple calculation for conduction of heat is examined. Consequently, this disagreement is attributed to cooling of the flat spring by radiation and thermal contact resistance of existing gap at the interface between the sample and piece.
We have carried out a photoelectron spectroscopy investigation of surface contamination on an aluminum film following transportation using a portable ultrahigh-vacuum transfer vessel. It was found that oxygen contamination was confined to about one atomic layer, and both hydroxylation and adsorption of carbon oxide were effectively suppressed. Although a hydrocarbon signal was detected, this originated from residual gas in the experimental equipment.
Electric conduction through Ru-complex self-assembled monolayer (SAM) was investigated by Au-nanoparticle (AuNP) bridge junction. Nonlinear current-voltage (I-V) characteristics exhibiting sharp threshold and steep rise with no zero-bias conductance was achieved by weak coupling between electrode and molecules. The observed I-V characteristics were well fitted by resonant tunneling model via HOMO level in wide range of temperature. The analysis by this curve fitting reveals that the work function of Au-nanoparticles was 0.32 eV larger than Au electrode and the thickness of SAM layer of tunneling barrier decrease as increasing temperature.
Transmission of highly charged ions through a glass capillary with the outlet size of 0.1 mmϕ was observed. Highly charged ions (HCIs, Ar9＋∼Ar14＋) were extracted from an electron beam ion source with the acceleration potential of 3 kV, and HCI beam in the 10 pA range was injected into the glass capillary. Transmitted current was in the several pA range, and the current density was about 5 times higher than the incident current density, however, it is necessary to improve unstable aspects such as limited operating time.
X-ray photoelectron spectroscopy (XPS), which is capable of analyzing the elemental composition and the oxidation states of surfaces and interfaces placed in a vacuum, was applied to observe ionic species dissolved in aqueous solutions. An environmental cell using a 5-nm thick silicon nitride membrane as a quasi-transparent window for incident x-rays and emitted photoelectrons was developed, and cesium chloride aqueous solutions with a variety of concentrations enclosed in the cells were measured using a laboratory-based XPS apparatus equipped with an Al-Kα source. Cs 4d photoelectrons emitted from cesium ions in the solutions were detected passing through the membrane. Moreover, the peak intensity increased proportionally with the concentration of cesium chloride, proving that this technique allows us to conduct quantitative analysis of solution species.
We have developed a novel nonevaporable getter named oxygen-free Pd/Ti. After activation at 133℃, oxygen-free Pd/Ti evacuates H2 and CO. Its pumping speeds do not decrease even after repeated cycles of activation and exposure to the air. Surface analysis by synchrotron radiation X-ray photoelectron spectroscopy showed that the carbon contamination decreased to an extent on heating in UHV, but decreased considerably on heating under an O2 pressure. The partial pressures of H2, CO, H2O, and CH4 in an oxygen-free-Pd/Ti coated chamber reduced to some degree after baking in UHV, but reduced remarkably after baking under an O2 pressure (O2 baking). Catalytic chemical reactions which remove carbon and hydrogen adsorbed on Pd surfaces appear to be responsible for the reduction of the partial pressures of H2, CO, H2O, and CH4. The pumping speeds of the oxygen-free Pd/Ti coated chamber for H2 and CO improved remarkably after O2 baking.