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Accelerator SIMS

Ender, R.M., DObeli, M., Suter, M., Synal, H. (1997) Accelerator SIMS at PSI/ETH Zurich. Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms, 123, 575-578. [Pg.938]

You can usually use the default values. If the calculation exceeds the iteration limit before it reaches the convergcriec limit, llieti th ere is m osl I ikely con vergeri ce failti re. Sim ply in creasin g tli e limits is un likely to help, I ll e nils COM vergeii ce accelerator, (see SCF Convergence on page 47), wli ich is available for all the SCF... [Pg.118]

In Secondary Ion Mass Spectrometry (SIMS), a solid specimen, placed in a vacuum, is bombarded with a narrow beam of ions, called primary ions, that are suffi-ciendy energedc to cause ejection (sputtering) of atoms and small clusters of atoms from the bombarded region. Some of the atoms and atomic clusters are ejected as ions, called secondary ions. The secondary ions are subsequently accelerated into a mass spectrometer, where they are separated according to their mass-to-charge ratio and counted. The relative quantities of the measured secondary ions are converted to concentrations, by comparison with standards, to reveal the composition and trace impurity content of the specimen as a function of sputtering dme (depth). [Pg.40]

In Dynamic Secondary Ion Ma s Spectrometry (SIMS), a focused ion beam is used to sputter material from a specific location on a solid surface in the form of neutral and ionized atoms and molecules. The ions are then accelerated into a mass spectrometer and separated according to their mass-to-charge ratios. Several kinds of mass spectrometers and instrument configurations are used, depending upon the type of materials analyzed and the desired results. [Pg.528]

The basic principle of e-beam SNMS as introduced by Lipinsky et al. in 1985 [3.60] is simple (Fig. 3.30) - as in SIMS, the sample is sputtered with a focused keV ion beam. SN post-ionization is accomplished by use of an e-beam accelerated between a filament and an anode. The applied electron energy Fe a 50 20 eV is higher than the range of first ionization potentials (IP) of the elements (4—24 eV, see Fig. 3.31). Typical probabilities of ionization are in the 0.01% range. SD and residual gas suppression is achieved with electrostatic lenses before SN post-ionization and energy filtering, respectively. [Pg.123]

In TOF-SIMS, the source of primary ions is pulsed at a rate of a few kHz. The pulse width is on the order of 1 ns. Secondary ions ejected from the sample surface are accelerated through a potential V and then drift through a field-free TOF analyzer with different velocities, depending on their masses. The drift velocity of an ion with charge-to-mass ratio zjm can be determined from the expression ... [Pg.296]

Positive SIMS spectra obtained from plasma polymerized acetylene films on polished steel substrates after reaction with the model rubber compound for times between zero and 65 min are shown in Fig. 44. The positive spectrum obtained after zero reaction time was characteristic of an as-deposited film of plasma polymerized acetylene. However, as reaction time increased, new peaks appeared in the positive SIMS spectrum, including m/z = 59, 64, and 182. The peaks at 59 and 64 were attributed to Co+ and Zn, respectively, while the peak at 182 was assigned to NH,J(C6Hn)2, a fragment from the DCBS accelerator. The peak at 59 was much stronger than that at 64 for a reaction time of 15 min. However,... [Pg.299]

SIMS) to map specific compounds in cross-sections, and atomic isotopic analysis for dating using accelerator mass spectrometry (AMS). [Pg.516]

The measurements that have been made at Rochester and the experience that has been gathered over the years on the operation of sputter ion sources [38] indicate that an analytical tool of unprecedented sensitivity and accuracy for isotopic ratio determinations can be constructed by coupling SIMS technology with the new accelerator technique. The only difference in principle between the experiments that have been conducted to date and the technique as it would be applied in secondary ion mass spectrometry is that the primary beam of cesium would be focussed to a fine probe of pm dimensions rather than the spot diameters of approximately 1 mm that have been used to date. [Pg.78]

The terms surface ionization mass spectrometry (SIMS) and ion sputtering are often used when accelerated atoms such as Xe or ions such as Ar+ strike a surface causing ionization of the material on the surface. The surface can be solid or liquid in the form of a solution or a suspension in the solvent. In this section, the terms fast atom bombardment (FAB) and fast ion bombardment (FIB) will be used. [Pg.353]

Spectroscopic developments have accelerated advances in the field of catalysis. This volume analyzes the impact on catalyst structure and reactivity of EXAFS, SIMS, MSssbauer, magic-angle spinning NMR (MASNMR), and electron-energy-loss vibrational spectroscopy. Many of these techniques are combined with other analytical tools such as thermal decomposition and temperature-programmed reactions. [Pg.7]

Figures were obtained for the 295-385 nm band of 280 and 333 MJ/m2/year for Florida and Arizona respectively. Combining these with figures given by Davis and Sims [7] for total irradiance in Fondon and Phoenix (75 and 175 kcalories/cm2/year, respectively) and making several assumptions, rough acceleration factors were calculated for artificial light sources ... Figures were obtained for the 295-385 nm band of 280 and 333 MJ/m2/year for Florida and Arizona respectively. Combining these with figures given by Davis and Sims [7] for total irradiance in Fondon and Phoenix (75 and 175 kcalories/cm2/year, respectively) and making several assumptions, rough acceleration factors were calculated for artificial light sources ...
Time of flight ion probes (TOF SIMS) have unique capabilities not found in other mass spectrometers. A pulsed ion beam, typically either cesium or gallium, ejects atoms and molecules from the sample. Ionized species are accelerated down the flight tube and the arrival time in the detector is recorded, giving the mass of the species (see discussion of time-of-flight mass analyzers above). TOF SIMS instruments used in cosmochemistry have spatial resolutions of <1 pm. They are used to determine elemental abundances in IDPs and Stardust samples. The spatial distribution of elements within a small sample can also be determined. TOF SIMS instruments can obtain good data with very little consumption of sample. [Pg.534]

Secondary ion sources (using primary ion beams to sputter solid sample surfaces) are applied not only in SIMS and SNMS, but also for the formation of negative ions in accelerator mass spectrometry (AMS). [Pg.65]

In SIMSLAB from VG Scientific, both surface analytical techniques - SIMS and SNMS - have been applied (see Figure 5.34). In this mass spectrometer different types of primary ion sources are available. Ar+, Cs+, Ga+ or O) primary ions are accelerated in the secondary ion source on the solid sample surface. Similar to the CAMECA IMS-7f, with this experimental arrangement, besides depth profiling, a microlocal analysis can also be performed. The sputtered secondary ions (for SIMS) or the post-ionized sputtered neutrals (for SNMS) - the post-ionization is carried out by an electron beam in an ionizer box (right-hand schematic in Figure 5.34) - are separated... [Pg.165]

Trace impurities including B, N, F, Mg, P, Cl, Cr, Fe, Ni, Co, Cu, Zn, Ge, As, Se, Mo, Sn and Sb in semiconductor materials (Si, SiGe, CoSi2, GaAs and GaN) can also be measured by TEAMS (trace element accelerator mass spectrometry), which utilizes a secondary ion source in an accelerator mass spectrometer.51 TEAMS is an interesting complementary technique to SIMS and can eliminate interferences that may not be resolvable in SIMS. [Pg.268]

Budding. J.V.. RJ. Hemley. arid H.K, Mao -High-Pressure Chemistry ol Hydrogen in Metals In Sim Sindy of Ivon Hydride" Santee. 421 (July 26. 19911. Crawloril. M "Accelerator Hye- tor Warhead Tritium. Srieme, 469 iJanuary 2". 9K9, ... [Pg.799]

Robinson MJ, Campbell F, Powell P, Sims D, Thornton C. Antibody response to accelerated Hib immunisation in preterm infants receiving dexamethasone for chronic lung disease. Arch Dis Child Fetal Neonatal Ed 1999 80(1) F69-71. [Pg.64]


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