Atomic scanning mode

Fig. 5 Statistical evaluation of LC-MS-based methods for tropane alkaloids referred in this chapter. (a) Relative frequency of ionization methods. +APCI positive atmospheric pressure chemical ionization, +ESI positive electrospray ionization, FAB fast atom bombardment, +TSP positive thermospray, (b) Relative frequency of scan modes used. MS full scan MS, MS/MS tandem mass spectrometry (product ion scan), MRM multiple reaction monitoring, SIM selected ion monitoring, (c) Relative frequency of mass analysers used. EBQtQ2 double focusing sector field mass spectrometer, IT ion trap, QqQ triple quadrupole, SQ single quadrupole. Considered publications were found by PubMed data-based search and references cited in these articles...

In the longer term, picoindentation instruments are likely to be widely used to extend the technique to a still smaller scale, with the help of techniques developed for atomic force microscopy. Already, plastic deformation at depths of a few atomic layers, as well as the effect of surface forces, have been quantified by means of depth-load measurements, using a point force microscope, i.e. an AFM operated in static (non-scanning) mode (Burnham Colton, 1989). 

Figure 6.4. The powder diffraction pattern collected from a sample of LaNi4 35800.15 using Cu Ka radiation on a Rigaku TTRAX rotating anode diffractometer. The divergence slit was 0.75° and the receiving slit was 0.03°. The experiment was carried out in a continuous scanning mode with a rate 0.5 deg/min and with a sampling step 0.02°. The powder used in this experiment was prepared by gas atomization from the melt and therefore, particles were nearly spherical (see inset in Figure 3.32).

To account for the presumably statistical distribution of Ni and Sn atoms in the 2(c) and 3(g) sites in this crystal structure, the initial distribution of atoms in the unit cell has been assumed as listed in Table 7.2. The initial profile and structural parameters are found in the input file for LHPM-Rietica on the CD, the file name is Ch7Ex01a.inp. Experimental diffraction data, collected on a Rigaku TTRAX rotating anode powder diffractometer using Cu Ka radiation in a continuous scan mode, are located on the CD in the file Ch7Ex01 CuKa.dat. 

End analysis by GC-MS of bromo and iodo derivatives of aromatic amines (Section III.B.4) show easily recognizable ions due to the presence of heavy atoms. A convenient alternative to GC-MS for end analysis of halogenated derivatives is by GC-ECD. The scanning mode acquisition MS of the brominated analytes show characteristic (n + 1)-multiplets with two mass unit separations for ions containing n Br atoms, stemming from the natural isotope distribution of this element. Analysis of halogenated derivatives showed that about 20 aromatic amines were present at ppb levels in industrial wastewater and ground water from a landfill and a former ammunition plant. In the latter case, most... 

Fast atom bombardment mass spectrometry. Fast atom bom-bardment/mass spectrometry (FAB/MS) analyses were performed on a VG ZAB-HF mass spectrometer equipped with an Ion Tech fast atom gun. Xenon gas was activated to 8 kv and 1.5 mA ion current for the fast atom generation. An accelerating voltage of 8 kV was applied to the FAB source. The mass spectrometer was scanned from 800 to 80 amu using an exponential down scan mode at 5 seconds per decade with a 1 second interscan time. The data were recorded with a PDP 11/24 computer and were processed with VG 11/250 software. 

Time-resolved measurements can be made at storage rings with high flux insertion devices that use a quick-scanning mode of operation of the monochromator [574]. In a reported study, products of Mo corrosion in KOH solution could be identified and quantified [578]. Application of time-resolved dispersive high-energy X-ray absorption fine structure (DXAFS) measurements on platinum nanoparticles in a fuel electrode have been described [575]. Results indicate severe surface reconstruction of the nanoparticle surface, showing at least three types of Pt-0 bonds (adsorbed OH, adsorbed atomic O and amorphous PtOx) under oxidative conditions. 

The single-crystal study of the a-Ni(NCS) (4-ViPy), structure was performed by using a Siemens AED aut omated three-circle diffractometer (filtered MoKa). 5029 independent reflections were measured within 27° of 0 by using the 0) - 20 scan mode, but as little as 950 reflections having 2a(I) have been used for structure analysis. The intensities were corrected for Lorentz-polarization effects but not for absorption. The structure was solved by direct methods, SHELX was used (ref. 5). Full-matrix refinement was made but, in view of low data/parameters ratio, only Ni, thiocyanates and pyridine N atoms were given anisotropic temperature factors. H atoms were included in the refinement at calculated positions. The final R value is 0.056 the weighted = 0.046 (w = 1.7/(a (F) + 0.0002(F) ). 

Several detectors are used for VOCs analysis by GC flame ionization detector (FID), photo ionization detector (PID), electron capture detector (BCD), electrolytic conductivity detector (ELCD), mass spectrometer detector (MSD or MS), and Fourier-transform infrared detector (FTIRD). For the in-depth reviews of the detectors, readers are directed to Refs. [52-54]. Examples of ICP-MS or microwave-induced plasma atomic emission spectrometry (atomic emission detector, AED) have been reported as detection technique after chromatographic separation [55,56]. Current trends and developments in GC analysis of VOCs have been recently reviewed by the group of Dewulf [16,57]. Mass spectrometer detectors allow low detection limits in single/selected ion monitoring (SIM) and a qualitative confirmation by full scan mode or by means of other ion selected as qualifier. 

In its most common mode of operation, STM employs a piezoelectric transducer to scan the tip across the sample (Figure 2a). A feedback loop operates on the scanner to maintain a constant separation between the tip and the sample. Monitoring the position of the scanner provides a precise measurement of the tip s position in three dimensions. The precision of the piezoelectric scanning elements, together with the exponential dependence of A upon c/means that STM is able to provide images of individual atoms. 

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