Ultra-high vacuum chambers, surface

In order to precise the effect of sulfur, an Auger analysis of the surface has been performed by transferring the sample in an ultra high vacuum chamber right before the... 

Nearly all the experiments described were performed in an ultra high vacuum chamber at pressures of about 10 10 torr. The specific equipment and experimental procedures used have been described elsewhere (7-9). Experimental protocol for the thermal desorption experiments and for the chemical displacement reactions is presented below. All these experiments were repeated with a control, blank experiment with a metal crystal that had the front and exposed face covered with gold the sides and back of the crystal were exposed (8,9). These blank experiments were performed to ensure that all thermal desorption and chemical displacement experiments monitored only the surface chemistry of the front exposed face of the metal crystal under study. 

The experiments were performed in an ultra-high vacuum chamber equipped with a high precision sample manipulator and a home made Mg Knudsen Cell along with in situ surface characterization tools like LEED, AES and EELS. The sample was cut (size 7x19x0.32mm3) from commercial Si (111) wafers with... 

Compared to other sampling techniques for surface investigations, a great advantage of IRRAS results from propagation of the probe photon in a non-vacuum environment. This enables the spectrometer to be set up outside an ultra-high vacuum chamber, which considerably simplifies operation. 

All of these techniques require an ultra-high vacuum chamber (10 to 10 Pa) to avoid contamination of the surface by undesired adsorption processes during the analysis. Vacuum conditions also limit the probability of accidental collisions between the emitted particles and gas molecules, which would lead to energy losses of the particles. 

Furthermore, surface studies on WC have shown the possibility of methanol and water adsorption, both essential to methanol electrooxidation catalysis [210-212]. It must be noted, however, that these studies were not conducted under electrode polarization conditions but in ultra high vacuum chamber. Electrochemical polarization experiments in which methanol was present were not given. 

Fig. 1. Small surface area sample mounted in an ultra-high vacuum chamber prepared for surface studies...

Because the positron moderator and the Ps converter require well characterized metal surfaces, the entire positron apparatus is in an ultra high vacuum chamber ( 2x10 torr). 

The evacuated spectrometer (p < 10 mbar) was attached to a small UHV chamber using calcium-fluoride windows. The small UHV chamber was part of a larger surface analysis system. The polymer films were produced in the vacuum system by vapor deposition and analyzed in ultra-high vacuum without exposure to air. 

The structures were grown in an ultra high vacuum (UHV) chamber VARIAN with a base pressure of 2-10 °Torr equipped with differential reflectance spectroscopy (DRS) [3] for a study of optical properties of the samples. Samples were cut from n-type 0.3 D cm Si(l 11) substrates. The silicon was cleaned by flashes at 1250 °C (7 times). Surface purity was controlled by AES. RDE was carried out at 500 °C, 550 °C, and 600 °C. The Cr deposition rate was about 0.04 nm/min controlled by a quartz sensor. An additional annealing during 2 min at 700 °C was done for all samples before the growth of silicon epitaxial cap layer. 

Experiments are performed in an ultra-high vacuum (UHV) chamber with a base pressure of better than 5 x 10 T. A pulsed molecular beam is used to dose gases on a thin film single-crystal surface of 200-nm thickness. Each pulse, which... 

The clusters that are collected via thermophoresis on the surface of a cold finger usually form very open, fractal structures. The clusters are held on the collector surface rather weakly, via Van-der-Waals forces, and are easily removed by means of a scraper. The material removed is consolidated in a compaction unit at typical pressures of 1-2 GPa the scraping and consolidation are carried out under ultra-high-vacuum conditions in-situ after the removal of the gas from the chamber, in order to maximize the cleanliness of the particle surfaces and the interfaces that are formed. 

SIMS requires an ultra-high vacuum environment, similar to AES and XPS. The ultra-high vacuum environment ensures that trajectories of ions remain undisturbed during SIMS surface analysis. The SIMS vacuum chamber and pumping system is not much different from that for AES and XPS. Figure 8.5 illustrates common SIMS structure in a vacuum chamber in which there are two main components a primary ion system and a mass analyzer system. The primary ion system includes a primary ion source, a Wien filter and ion beam deflector. The mass analysis system includes a secondary ion extractor filter, mass analyzer and ion detector. 

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