Source region

A schematic diagram of a simple TOP instrument is shown in figure B 1.7.17(a). Since the ion source region of any instrument has a finite size, the ions will spend a certain amount of time in the source while they are accelerating. If the... 

Ions generated in the ion source region of the instrument may have initial velocities isotropically distributed in tliree dimensions (for gaseous samples, this initial velocity is the predicted Maxwell-Boltzmaim distribution at the sample temperature). The time the ions spend in the source will now depend on the direction of their initial velocity. At one extreme, the ions may have a velocity Vq in the direction of the extraction grid. The time spent in the source will be... 

Figure 3 shows the substantial spatial variability in NFlj emissions, particularly in source regions. It is clear that maps at a lower resolution, which are often made (e.g. 20 km grids for the 150 km grids for Europewill artificially smooth... 

Figure 2 Schematic view of the ion source region of the LIMS instrument in the PAI configuration.

Figure 2 presents a schematic view of the ion source region in the PAI configuration. A second high-irradiance, frequency quadrupled pulsed Nd—YAG laser is focused parallel to and above the sample surface, where it intercepts the plume of neutral species that are produced by the ablating laser. Appropriate focusing optics and pulse time-delay circuitry are used in this configuration. 

Several ion sources are particularly suited for SSIMS. The first produces positive noble gas ions (usually argon) either by electron impact (El) or in a plasma created by a discharge (see Fig. 3.18 in Sect. 3.2.2.). The ions are then extracted from the source region, accelerated to the chosen energy, and focused in an electrostatic ion-optical column. More recently it has been shown that the use of primary polyatomic ions, e. g. SF5, created in FI sources, can enhance the molecular secondary ion yield by several magnitudes [3.4, 3.5]. 

NOj) are exported from the source regions. For example, Honrath and Jaffe (1992) found elevated concentrations of nitrogen oxides at Barrow, Alaska during spring, as compared to summer. This is largely due to decreased removal processes during winter for some nitrogen oxides, such as peroxyacetyl nitrate. 

In Equation 5.2.2, it is assumed that acoustic wavelengths A are large when compared with any of the characteristic scales of the flow (A L) and that the measurement point r is far from the source region (r /l). The previous expression provides the sormd pressure in the far-field for a compact source, but it can be used indifferently for premixed or nonpremixed flames [30]. 

If the observation point is in the far-field and if the source region is compact, the previous expression becomes... 

Wet deposition of THg from 4 Swedish and 1 Finnish station is presented in Figme 2.6. The stations are located in a south-to-north gradient with increasing distance from the main source regions. 

Camp, V.E. (1995) Mid-Miocene propagation of the Yellowstone mantle plume head beneath the Columbia River basalt source region. Geology, 23, 435-438. 

Davies JH, Biekle MJ (1991) A physical model for the volume and composition of melt produeed by hydrous fluxing above subduction zones. Phil Trans R Soc Lond 335 355-364 Davies JH, Stevenson DJ (1992) Physical model of source region of subduction zone voleanies. J Geophys Res 97 2037-2070... 

Cole JE, Rind D, Webb RS, Jonzel J, Healy R (1999) Climahc controls on interatmual variability of precipitahon 5180 Simnlated inflnence of temperature, precipitahon amount, and vapor source region. J Geophys Res 104 14223-14235... 

Figure 3. Trichloroethylene isopleths representing impact patterns from a single specific source. Region Beaumont, Texas/Lake Charles, Louisiana (shear test region). Concentrations from 1, specific point sources 0, prototype point sources 0, area sources. Key UG/M ...

Figure 5. Isopleths of net hazard from all chemical sources. Region Beaumont, Texas/ Lake Charles, Louisiana (shear test region). Key Hazard Level 1, 5.00E-10 2, 1.00E- 3, 2.50E-9 4, 5.00E-9 5, 1.00E-8 6, 2.50E-8 7, 5.00E-8 8, 10.00E-8 9, 1.75E-7.

Source Region Field Free Region Detector... 

The value for the charge of the electron is a constant. In many experiments the voltage applied across the ion-source region is also a constant. Thus we can simplify (3.4) to give... 

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