Thermal ionization schematic

Figure 2.1. Schematic of a thermal ionization (Tl) source. Each filament consists of two pins connected by a wire.

Figure 1. Schematic representation of the calcium mass spectrum in (a) natural materials, (b) a Ca- Ca tracer solution used for separating natural mass dependent isotopic fractionation from mass discrimination caused by thermal ionization, and (c) a typical mixture of natiwal calcium and tocer calcium used for analysis. The tracer solution has roughly equal amounts of Ca and Ca. In (c) the relative isotopic abundances are shown with an expanded scale. Note that in the mixed sample, masses 42 and 48 are predominantly from the tracer solution, and masses 40 and 44 are almost entirely from natural calcium. This situation enables the instrumental fractionation to be gauged from the Ca/ Ca ratio, and the natural fractionation to be gauged from the sample Ca/ Ca ratio.

Figures 3.5 and 3.6 present schematic classification of regimes observable for the A + B —> 0 reaction. We will concentrate in further Chapters of the book mainly on diffusion-controlled kinetics and will discuss very shortly an idea of trap-controlled kinetics [47-49]. Any solids contain preradiation defects which are called electron traps and recombination centres -Fig. 3.7. Under irradiation these traps and centres are filled by electrons and holes respectively. The probability of the electron thermal ionization from a trap obeys the usual Arrhenius law 7 = sexp(-E/(kQT)), where s is the so-called frequency factor and E thermal ionization energy. When the temperature is increased, electrons become delocalized, flight over the conduction band and recombine with holes on the recombination centres. Such...

Schematic representation of a thermal ionization cavity source.

Figure 11.6 Chemical reactions accelerated under heating for real-time MS monitoring, (a) Schematic diagram of the paper-assisted thermal ionization setup. (A) Heated metal probe, (B) filter paper, and (C) home-made pipette tip. (b) Proposed mechanism of the Eschweiler-Clarke reaction [58]. Reproduced from Pei, j., Kang, Y., Huang, C. (2014) with permission of the Royal Society of Chemistry.

The generalization to the case of a thermally averaged parent state describes an interesting modulation curve that reflects in position and width the rotational eigenvalue spectrum of the resonant intermediate [31]. This structure has been observed in studies of HI ionization in Ref. 33. A schematic cartoon depicting the excitation scheme and the form of the channel phase for the case of a thermally averaged initial state is shown in Fig. 5g. 

Two models can explain the events that take place as the droplets dry. One was proposed by Dole and coworkers and elaborated by Rollgen and coworkers [7] and it is described as the charge residue mechanism (CRM). According to this theory, the ions detected in the MS are the charged species that remain after the complete evaporation of the solvent from the droplet. The ion evaporation model affirms that, as the droplet radius gets lower than approximately 10 nm, the emission of the solvated ions in the gas phase occurs directly from the droplet [8,9]. Neither of the two is fully accepted by the scientific community. It is likely that both mechanisms contribute to the generation of ions in the gas phase. They both take place at atmospheric pressure and room temperature, and this avoids thermal decomposition of the analytes and allows a more efficient desolvation of the droplets, compared to that under vacuum systems. In Figure 8.1, a schematic of the ionization process is described. 

Figure 2.26 a) Experimental arrangement of a single-filament thermal surface ionization source b) Schematic diagram of a double-filament arrangement for thermal surface ionization. (H. Kienitz (ed.), Massenspektrometric (1968), Verlag Chemie, Weinheim. Reproduced by permission of Wiley-VCH.)... 

Figure 14.8 Schematic diagram of the natural gas analyser system SL, sample loop VI, two-way valve to block the sample lines V2, ten-port valve V3, V4 and V5, six-port valves R, restriction TCD, thermal-conductivity detector FID, flame-ionization detector.

Fig. 17. Schematic representation of the experimental equipment for transmission UV-VIS studies on zeolites. C Quartz cuvette IM ionization gauge CM capacitance manometer IP ion pump TM thermal conductivity gauge SP sorption pump MP mechanical pump 1 -4 gas inlet valves. From [30] reproduced by permission of The Royal Society of Chemistry...

Figure 7.3 shows a schematic diagram of a typical FPD. The detector consists of a hydrogen inlef air inlet, sample inlet, burner, thermal filters, light filter, PMT, signal processor, and exhaust chimney. A source of hydrogen is required to produce the hydrogen-air flame for sample ionization. 

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