Time-of-flight , analysis

The incident ions cause recoil in the surface atoms. In studies of ionic liquids, only direct recoil - that is, motion in the forward direction - was measured. Watson and co-workers [56, 57] used time-of-flight analysis with a pulsed ion beam to measure the kinetic energies of the scattered and sputtered ions and therefore determine the masses of the recoiled surface atoms. By relating the measured intensities of the... 

All analyzers use one or more of three basic principles (a) magnetic analysis, (b) electrostatic analysis, and (c) time-of-flight analysis. Magnetic analyzers of single and double focusing types are by far the most common ones currently in use, and will serve to illustrate the methods of analysis. Two other types of analyzers which have gained popularity for analytical applications but are omitted in the fol-... 

Enhanced molecular ion implies reduced matrix interference. An SMB-El mass spectrum usually provides information comparable to field ionisation, but fragmentation can be promoted through increase of the electron energy. For many compounds the sensitivity of HSI can be up to 100 times that of El. Aromatics are ionised with a much greater efficiency than saturated compounds. Supersonic molecular beams are used in mass spectrometry in conjunction with GC-MS [44], LC-MS [45] and laser-induced multiphoton ionisation followed by time-of-flight analysis [46]. 

In principle, MALDI-TOF (MALDI-Time Of Flight) analysis allows for the determination of the complete polymer mass distributions and, from that, the calculation of various molecular weight averages like Mn and Mw and the... 

In principle, the neutral desorbed products of dissociation can be detected and mass analyzed, if ionized prior to their introduction into the mass spectrometer. However, such experiments are difficult due to low ejfective ionization efficiencies for desorbed neutrals. Nevertheless, a number of systems have been studied in the groups of Wurm et al. [45], Kimmel et al. [46,47], and Harries et al. [48], for example. In our laboratory, studies of neutral particle desorption have been concentrated on self-assembled monolayer targets at room temperature [27,28]. Under certain circumstances, neutrals desorbed in electronically excited metastable states of sufficient energy can be detected by their de-excitation at the surface of a large-area microchannel plate/detector assembly [49]. Separation of the BSD signal of metastables from UV luminescence can be effected by time of flight analysis [49] however, when the photon signal is small relative to the metastable yield, such discrimination is unnecessary and only the total yield of neutral particles (NP) needs to be measured. 

Sinha, P. Poland, J. Schnolzer, M. Rabilloud, T. A new silver staining apparatus and procedure for matrix-assisted laser desorption/ionization-time of flight analysis of proteins after two-dimensional electrophoresis. Proteomics (Germany) 2001, 1(7), 835-840. 

Fig. 4.5.8 Examples for structures and molecular masses of 2-aminobenzamide (2-AB)-labelled oligosaccharide moieties derived from serum transferrin. Values below the oligosaccharide structures indicate the expected masses (in Da) by matrix-assisted laser desorption ionisation - time of flight analysis.

Bahr, U., and Karas, M. (1999). Differentiation of isobaric peptides and human milk oligosaccharides by exact mass measurements using electrospray ionization orthogonal time-of-flight analysis. Rapid Commun. Mass Spectrom. 13 1052-1058. 

Fig. 3. A schematic view of a crossed-molecular beam apparatus used for studying the reactions of chlorine atoms with halogen molecules. The mass spectrometer detector is rotatable about the scattering centre for measuring the angular distributions of the reaction products whose recoil velocities are determined by time-of-flight analysis. (Reproduced from ref. 558 by permission of the authors and the American Institute of Physics.)...

A great deal of efforts were made to imderstand the systematics of this new method. Fig. 5 and Table 1 give some such examples. The detail of the analysis can be formd in Reis. [29,30]. The resulting DS fusion time spectrum and its comparison with Monte Carlo (MC) simulations are shown in Fig. 6, which clearly estabhshes the resonance structure. From the time-of-flight analysis of 2036 116 DS fusion events, a formation rate consistent with 0.73 (0.16), easi(0.09), odeJ times the theoretical prediction of Faifman et al. [9] was obtained (the first error... 

M.D. Miller, et al., Matrix-assisted laser desorption/ionization time-of-flight analysis of the copolymerization reaction of an expanding monomer with a diepoxide. J. Polym. Sci. A Polym. Chem. 2005, 43(23), 5962-5970. 

In practice, these three functions are achieved using the wave/particie duality of the neutron. The incident and scattered wave vectors can be determined by Bragg reflection from single crystals or by time of flight analysis of their velocity. 

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