Fragmentation distribution pattern

Table 5.2 Fragment distribution pattern of water vapour for ionising electron energy = 102 e V...

Table 5.3 Fragment distribution pattern for several gases for different ionising electron energiesa...

A free-field blast wave emanates from an explosion until it reaches an object and interacts with it. Sources of explosions that have very high energy and power densities produce ideal blast waves that have predictable properties. A blast wave decays with distance from the source. For high explosive materials, the distance for a blast wave is related to the cube root of the charge weight. In some cases, one can estimate the forces involved in an explosion from the fragment distribution pattern. 

Using the method mentioned above, the effect of photoabsorption by sulfur atoms in amino acids was studied by Yokoya et al. [29]. They chose cystathionine as a model molecule because of the structural advantage that most of the decomposed fragments are easily detectable amino acids. A comparison of the distribution pattern of fragments between on-resonance and off-resonance lead to the conclusion that cystathionine was more frequently cleaved around a sulfur atom than at a bond apart from the sulfur. 

The two naturally occurring isotopes of Gallium Table 2 can be used as an aid in mass spectroscopic studies. Isotopic distribution patterns have been used to model the masses and abundances of the isotopes for a given formula, and as a fingerprinting tool when used in a comparative analysis with the experimental data. This technique has recently been used for identifying the formation, mechanism, and the fragmentation pattern of Ga clusters (Figure 2), and more recently to confirm the formation of the first Ga=As... 

In order to investigate intact neutral ablated products one has to ionize the molecules as gently as possible to avoid secondary decomposition by laser. In this sense, often used MPI techniques are not suited, as mentioned briefly in Section 9.2 intense electric fields of MPI pulses tend to cause extensive fragmentation of the ablated products. Moreover, accidental resonance enhancement of some specific mass peaks may distort the true mass distribution pattern. 

Particle size analysis is useful for assessing attrition because both fragmentation and fine formation yield separate particle populations with different sizes. Production of midsize particles by means of shattering will lower the particle population s mean size and increase its size spread, as formation of fines through surface erosion will make the overall size distribution bimodal or multimodal. Barletta et al. (1993b) summarizes the different size distribution patterns in attrition resulting from the predominant attrition mechanisms and reviews the different models that fit these distributions. 

Isotopic ions The substance s elemental composition is derived from the relative abundance of isotopic ions. The paesence of Cl, Br, S or Si can be easily determined from the isotopac peak pjattem. A quality requirement of a mass spectrum is the dear distinction of isotopac ions. The isotopic distribution pattern pjermits congener distinction in the analysis of px)lychlorinated biphenyls (PCB). The successive loss of chlorine atoms and the formation of the corresponding (M-nCl)+ fragments distinguishes individual congeners. 

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