Mass spectra energy

Time-of-flight mass spectrometers have been used as detectors in a wider variety of experiments tlian any other mass spectrometer. This is especially true of spectroscopic applications, many of which are discussed in this encyclopedia. Unlike the other instruments described in this chapter, the TOP mass spectrometer is usually used for one purpose, to acquire the mass spectrum of a compound. They caimot generally be used for the kinds of ion-molecule chemistry discussed in this chapter, or structural characterization experiments such as collision-induced dissociation. Plowever, they are easily used as detectors for spectroscopic applications such as multi-photoionization (for the spectroscopy of molecular excited states) [38], zero kinetic energy electron spectroscopy [39] (ZEKE, for the precise measurement of ionization energies) and comcidence measurements (such as photoelectron-photoion coincidence spectroscopy [40] for the measurement of ion fragmentation breakdown diagrams). 

Accelerating voltage (high voltage) scan. An alternative method of producing a momentum (mass) spectrum in magnetic-deflection instruments. This scan can also be used, in conjunction with a fixed radial electrical field, to produce an ion kinetic energy spectrum. 

The energy difference between diazirine and diazomethane, interesting from the point of view of their isomerism, came from MS measurements (63JCP(39)3534). The appearance potentials of the CH2 ion, common to both compounds, yielded a difference in heats of formation of 125kJmor A strong peak in the mass spectrum of 3-chloro-3-methyl-diazirine (50) with relative mass 55 was ascribed to the methyldiazirinium ion (51). 

Mass spectrum obtained from the NIST Hasteloy Ni-basad standard alloy, using electron-gas SNMSd (Laybold INA-3). The sputtering energy was 1250 V, increasing the sputtered atom flux at the expense of depth resolution. Matrix ion currents ware about 10 cps, yielding background limHed detection at about 2 ppm. 

Figure 4 Mass spectrum obtained from the Aiuminium Peehiney standard Ai 11630, using eiectron-gas SNMSd with a sputtering energy of 1250 V. The AI matrix ion currerrt was significantly greater than 10 cps. yielding a background courrt rate limit less than 1 ppm.

Fragmentation (mass spectrum), 410-413 Free radical, 139 Free-energy change (AG), 153 Free-energy change (AG°), standard, 153... 

Mass-energy relationship, 121 Mass number, 90, 120 Mass spectrograph, 242, 443 Mass spectrum of neon, 242 Matter... 

We conclude, that the ionization processes by charge exchange in a perpendicular type apparatus or using electron impact at high energy are substantially similar, and therefore it is possible to calculate the electron impact mass spectrum from charge exchange observations by... 

Figure 6. Mass spectrum of C2Ha as a function of energy (e.v.) (19)...

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