Thermal Vaporization Source

Fig. 5. Thermal vaporization sources (a) hairpin (b) spiral (c) basket (d) boat and (e) canoe, which ate all resistively heated sources and (f) focused...

Thermal treatment. See Heat treatment copper-beryllium alloys, 3 654 nickel-beryllium alloys, 3 657-658 of macrofouling organisms, 26 150 Thermal vaporization sources, 24 727 Thermal vaporization rate, 24 725 Thermal waste treatment, 25 831-834, 843-845... 

Since these mass discrimination effects are largely a function of the vaporization process the same discrimination and correction techniques would be applicable to the resonance ionization processes that utilize thermal vapor sources ... 

Vacuum evaporation (including sublimation) is a PVD process where material from a thermal vaporization source reaches the substrate without collision with gas molecules in the space between the source and substrate. The vacuum is required to allow the molecules to evaporate freely in the chamber and then subsequently condense on all surfaces... 

Figure 6.7 Resistively Heated Thermal Vaporization Source Configurations...

For example, the deposition of cadmium on a steel surface having a temperature greater than 200°C results in total re-evaporation of the cadmium. By placing hot surfaces (mirrors) around a 3D substrate, cadmium can be deposited out of the line of sight of the thermal vaporization source. 

Charge (evaporation) The material to be vaporized and that is placed in a thermal vaporization source. See also Evaporation to completion. 

Effusion cell A thermal vaporization source that emits vapor through an orifice from a cavity where the vapor pressure is carefully controlled by controlling the temperature. Used in molecular beam epitaxy (MBE) processing. Also called a Knudsen cell. 

Fig. 1. Pressure required for propagation of decomposition flame through commercially pure acetylene free of solvent and water vapor in long horizontal pipes. Gas initially at room temperature ignition by thermal nonshock sources. Curve shows approximate least pressure for propagation (0), detonation,...

Most elements thermally vaporize as atoms but some, such as Sb, C, and Se, have a portion of their vapor as clusters of atoms. For these materials, special vaporization sources, called baffle sources, can be used to ensure that the depositing vapor is in the form of atoms by causing the material to be vaporized from multiple hot surfaces before it leaves the source. 

Thermal ignition sources A source that will cause the ignition of a flammable gas, vapor, or dust, such as an electric spark, flame, or hot surface. 

An important method for producing semiconductor layers is the so-called molecular beam epitaxy (MBE) (see [3,12-14] and [15-19]). Here, atoms of the same or of a different material are deposited from the vapor source onto a faceted crystal surface. The system is always far from thermal equilibrium because the deposition rate is very high. Note that in this case, in principle, every little detail of the experimental setup may influence the results. 

Another thin film technology based nanoparticle preparation route is gas condensation, in which metal vapor is cooled to high levels of supersaturation in an inert gas ambient [126-128]. In these experiments particles necessarily nucleate in the gas phase. In a promising extension of this technique a pulsed laser beam replaces the conventionally used thermal metal vapor source [120,121,129-134]. 

The anionic species ROCS2 resulted from O-alkyl(aryl) esters of the hypothetical dithiocarbonic acids, ROC(S)SH, better known as xanthates, are versatile ligands and they generate an extensive coordination chemistry. The interest for metal xanthates is stimulated by their potential use as single source precursors for nanoscopic metal sulfides in photochemical or thermal vapor deposition systems under mild conditions,218 221 e.g. for Zn,222 Cd,223 In,224... 

The following discussion will be concerned primarily with applications of the ms/ms technique in the synfuel area. Attempts will be made to illustrate the unique capabilities of the ms/ms analysis with examples taken from our work on coal liquefaction products. Figure 5 shows the positive ion chemical ionization (PCI) mass spectrum of the coal liquid in question (SRC II mid heavy distillate, total bottoms). This spectrum is actually the normalized sum of approximately 500 individual mass spectra taken while the SRC II was thermally vaporized from a solids probe into the source of a mass spectrometer, and represents the molecular weight profile of this distillate fraction. Since isobutane Cl gives to a first approximation only protonated molecular ions (and no fragment ions), the peaks represent the individual components in the SRC II arranged incrementally by molecular weight. 

Blakely and Vestal [24] employed the thermospray system with the quadrupole mass spectrometer and demonstrated that it could provide stable vaporization and ionization at flow rates up to 2 ml/min with an aqueous mobile phase. If the mobile phase contained a significant amount of ions in solution ca. 10 to 1.0 M) no extra thermal ionization source is required to achieve detection of many non-volatile solutes at the sub-microgram level. They found that with weakly ionized mobile phases, a conventional electron beam needs to be used to provide gas-phase reagent ions for the chemical ionization of the solute. The thermospray system has been effectively used by Voyksner et al. [25] in the analysis of cancer drugs. 

Hi) Methods based on mass spectrometry Spark-source mass spectrometry Glow-discharge mass spectrometry Inductively coupled-plasma mass spectrometry Electro-thermal vaporization-lCP-MS Thermal-ionization mass spectrometry Accelerator mass spectrometry Secondary-ion mass spectrometry Secondary neutral mass spectrometry Laser mass spectrometry Resonance-ionization mass spectrometry Sputter-initiated resonance-ionization spectroscopy Laser-ablation resonance-ionization spectroscopy... 

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