Oxygen mapping

Figure 6.17. Energy filtered nitrogen and oxygen maps of a poly(styrene-co-acrylonitrile)-poly(carbonate) (SAN-PC) blend showing part of a PC particle in the SAN matrix. The TEM was a Zeiss 912 with an Omega filter (From Libera and Disko [335] reproduced with permission.)...

An elecfrosfafic pofenfial map shows fhe equivalence of fhe fwo fermmal oxygens Nofice loo fhaf fhe cenfral oxygen is blue (posifively charged) and bofh fermmal oxy gens are red (negafively charged)... 

FIGURE 4 2 Electro static potential maps of methanol and chloro methane The electrostatic potential is most negative near oxygen in methanol and near chlorine in chloromethane The most positive region is near the O—H proton in methanol and near the methyl group in chloromethane... 

Find the molecular model of 18 crown 6 (see Figure 16 2) on Learning By Modeling and examine its electrostatic potential map View the map in vanous modes (dots contours and as a transparent surface) Does 18 crown 6 have a dipole moment Are vicinal oxygens anti or gauche to one another"d... 

Lone pair donation from the hydroxyl oxygen makes the carbonyl group less elec trophilic than that of an aldehyde or ketone The graphic that opened this chapter is an electrostatic potential map of formic acid that shows the most electron rich site to be the oxygen of the carbonyl group and the most electron poor one to be as expected the OH hydrogen... 

FIGURE 19 4 Electro static potential maps of (a) acetic acid and (b) acetate ion The negative charge (red) IS equally distributed between both oxygens of acetate ion The color range IS different for (a) and (b)... 

Electron delocalization in carboxylate ions is nicely illustrated with the aid of elec trostatic potential maps As Figure 19 4 shows the electrostatic potential is different for the two different oxygens of acetic acid but is the same for the two equivalent oxygens of acetate ion... 

Structure. The straiued configuration of ethylene oxide has been a subject for bonding and molecular orbital studies. Valence bond and early molecular orbital studies have been reviewed (28). Intermediate neglect of differential overlap (INDO) and localized molecular orbital (LMO) calculations have also been performed (29—31). The LMO bond density maps show that the bond density is strongly polarized toward the oxygen atom (30). Maximum bond density hes outside of the CCO triangle, as suggested by the bent bonds of valence—bond theory (32). The H-nmr spectmm of ethylene oxide is consistent with these calculations (33). 

Fig. 2.30. SAM map offractured SiC after sintering with B addition [2.167], (a)-(d) elemental maps in boron, potassium, sodium, and oxygen, respectively. (E), (F) point analyses at points A and B, respectively.

The oxygen ion beam diameter is limited to 0.5 pm by the duoplasmatron source used. For mapping electropositive elements this drawback must be tolerated because of the chemical enhancement effect. 

An electrostatic potential map shows the equivalence of the two terminal oxygens. Notice, too, that the central oxygen is blue (positively charged) and both terminal oxygens are red (negatively charged). 

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