Typical Mass Spectra

1 0 Important peak formed by 2H rearrangement (C H2 , loss. Section 4.10) Important odd-electron ion series 

0 Peak formed by sigma electron ionization a Peak formed by alpha cleavage 

Try one more unknown, 3.6, before tackling the next important area, Mechanisms. 

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Figure 4. Typical mass spectra before (lower) and during (upper) UV irradiation of PMMA at 50°C without C>2 gas.

FIGURE 11.46 Typical mass spectra of ambient air (a) without collisional dissociation of the adducts and (b) with collisional dissociation. The counts for NO, and its adducts with HNO, are shown in parentheses in (a). Note changes in scale from linear to logarithmic (adapted from Tanner et al., 1997). 

Figure 5.(a) Typical mass spectra of a 0.9 im borophosphoro silica glass (b) weight % concentrations of B and P compared with chemical analysis, EDX and WDX at various diboran flow rates. 

Typical mass spectra fragments from saccharides are likely to have the following structures ... 

Fig. (5). Typical mass spectra from the Drosophila hemolymph (0.1 pL) collected from a single fly at 6h, 24h post challenge and from a control (unchallenged) fly. MALDI mass spectra were acquired with a sandwich sample preparation and a-cyano-4-hydroxycinnamic acid as matrix. Numbers (1-24) correspond to the Drosophila immune-induced molecules (DIMs).

Such a peak-to-peak resolution can be observed up to a molecular weight of the polymer of 20 000, but above this value spectra generally show continuous distribution. Typical mass spectra obtained from a biopolymer, insulin, and from a synthetic polymer, poly(isobutylcyanoacrylate), are shown in Figure 2.5. 

As we now look at typical mass spectra of the classes of organic compounds we have seen so far, keep the following two points in mind. They provide valuable information about the molecular composition of an unknown compound. 

Real-Time Detection of Laser-Pulse-Induced Molecular Dynamics. To study silver aggregates the amplified laser pulses are, for example, efficiently 40%) frequency-doubled in a BBO crystal. The second harmonic is split into pump and probe pulses, with the probe pulse delayed with respect to the pump pulse by a computer-controlled translation stage. The pump and probe laser beams are imaged into the trap collinearly with the ion trajectories and overlap throughout the whole length of the trap (see Fig. 2.26). The electrons of the stored cluster anions are detached by the pump pulse and, subsequently, after a certain delay time At, the newly created neutrals are ionized by the probe pulse. This is achieved by nonresonant TPI rather than by REMPI [281, 282]. Figure2.34 presents typical mass spectra for silver anions and cations. 

Fig. 8d shows two typical mass spectra recorded dming the desorption of soot or trapped gaseous PAHs. The chosen parameters (Ed=0.3 mJ/pulse, Eion=0.5 mJ/pulse) simultaneously ensme smooth desorption (the signals disappear after few laser shots) and fi agment-free spectra (no signal has been evidenced at low mass). These speetra are at least qualitively... 

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