SSIMS spectra

Fig. 3.7. SSIMS spectra after interaction ofoxy- bed on silver, at 400 K [3.16] (A) positive SSIMS gen with Haifa monolayer of potassium adsor- spectrum (B) negative SSIMS spectrum.

In conclusion, SSIMS spectra provide not only evidence of all the elements present, but also detailed insight into molecular composition. Quasimolecular ions can be desorbed intact up to 15000 amu, depending on the particular molecule [3.17] and on whether an effective mechanism of ionization is present. Larger molecules can be identified from fragment peak patterns which are characteristic of the particular molecules. If the identity of the material being analyzed is completely unknown, spectral interpretation can be accomplished by comparing the major peaks in the spectrum with those in a library of standard spectra. 

Fig. 3.8. SSIMS spectra from oxide (A) positive SSIMS spectrum, 3 s ...

Figure 2 shows positive SSIMS spectra obtained from the Si and Cr surfaces before heating of the substrate in vacuum. Table 1 gives the chemical formulae for the positive ions identified in the figure. 

Figure 3 shows the negative SSIMS spectra obtained from Si and Cr surfaces at room temperature. Table 2 shows the chemical formulae for the peaks identified in Fig. 3. The negative ion spectra from these surfaces are again found to be very similar. Comparison of Figs 3(a) and (b) shows that the Cr and Si surfaces yield similar 3-APTHS related ions with roughly comparable intensities. Negative ions consistent with a chromium native oxide were also observed for the Cr surface. Parent ions due to 3-APTHS were absent from both the positive and negative SSIMS spectra. No dimer, trimer, or higher molecular weight...

Figure 3. Negative SSIMS spectra for 3-APTHS films studied (a) Si, (b) Cr. The spectra were acquired at room temperature. Curves (a) and (b) are plotted on the same relative intensity scale. The absolute intensity scale is arbitrary. 

Labelling the 3-APTHS molecule with "OH groups provides an isotopic tag at the site on the molecule where cross-linking should take place. 3-APTHS hydrolyzed in 97.8 at %, 80 labelled water was spun onto sample substrates in the manner described above and SSIMS spectra were acquired both at room temperature and after heating of the sample to 100°C in vacuum for 1 h. The relative intensity of the oxygen containing ions produced by these samples can be... 

Fig. 21 Positive SSIMS spectra of PE and PE/C11 ( ) samples. Here, PE-Ar 5 and PE/ Cll( )-Ar 5 indicates PE and PE/C11 ( ) samples treated with an argon plasma for 5 s, whereas PE-Ar 5 and PE/Cll( )-Ar 5, washed indicates samples that were subsequently washed with an aqueous solution of 0.1 mM HC1...

The immobilisation of unsaturated surfactant sodium 10-undecenoate [Cl 1( )] and the saturated surfactant sodium dodecanoate (C12) was carried out on PE surfaces [266] by means of an argon plasma treatment and characterised using XPS and SSIMS techniques. The typical SSIMS spectra for unmodified and modified PE films are shown in Fig. 21. The differences in the SSIMS spectra of PE and that of PE/C11( ) and PE/C11( )-Ar 5 are merely the spectra of the surfactant which can be attributed to the presence of a layer of Cll( ) on the PE sample. The SSIMS analysis showed that during... 

Polymer surface characterization. The positive and negative ion SSIMS spectra of the HPC film are shown in Figures 1 and 2. 

Previous work (11-16) has regarded the negative ion SSIMS spectra as relatively uninformative in comparison to positive ion emission. In this study we confirm very recent findings (18) that important information on side chain and backbone structure may indeed be obtained on analysis of the negative cluster ions which both compliments and clarifies information previously only obtainable from positive ion emission. The negative ion SSIMS spectrum shows a large amount of structural information without the confusing presence of intense C H species which abound in the positive ion spectrum. 

For comparison, the positive ion SSIMS spectra of the HPMC molecule is shown in Figure 3. Despite the considerably lower degree of hydroxypropyl substitution that exists for the previous HPC molecule, the presence of the 59D ion is still clearly distinguishable. More significantly, the higher degree of methoxyl content is reflected in the intense 45D ion. 

FIG. 17 Positive ion SSIMS spectra of PHB microparticles (a) uncleaned, (b) dialysis cleaned (c) ultrafiltration cleaned (d) GPC cleaned. (From Rel. 44.)... 

In the negative ion SSIMS spectra of these polymers, the most notable ions are the [M-H] appearing at m/z 115, 171 and 205 for the free acid, buril and benz)d derivatives respectively and the [M+OH]" cation at m/z 133, 189 and 223, as before. The [M+H]" and [M+0-H] ions are very weak for these polymers and the reasons for this are obscure. There is also a strong ion appearing at m/z 107 for the benzyl derivative which is due to the benzyl oxide anion. 

The positive ion spectra of the three PMA derivatives show little difference between each other below m/z = 100, with the exception that the benzyl derivative has an intense peak at m/z 91 which is assigned to the C7H7+ tropyllium ion commonly observed in SSIMS spectra of compounds containing benzyl groups. The only readily assignable ions of interest observed at higher mass are tire [M+H] ions observed for the butyl and free acid, and the [M-OH]+ and [M+0-HJ+ for the butyl derivative. The benzyl derivative does not display any of these ions, and none of the polymers demonstrated strong radical cations. 

In the SSIMS spectra of these blends all of the ions diagnostic of PLA and PSA were observed. It was demonstrable that there was a surface excess of PLA in all of the blends by examining the relativ e intensities of each set of ions in accordance witlt the XPS results. However, even in high weight % PLA blends it was possible to observ e PSA derh ed ions and this may result from the extension of PSA domains to the top 10 nm of the surface, or due to a small but detectable concentration of PSA in the PLA domains. 

Figure 51. SSIMS spectra from a cleaned nickel target, under conditions of 3 keV primary argon ion energy and 5x10" A primary current [182J...

Figure 53. SSIMS spectra following interaction of oxygen with half a monolayer of potassium adsorbed on silver, at 300 K 1184]...

Figure S4. SSIMS spectra from oxide nims formed on aluminum after anodization treatment in phosphoric acid for 3 or 5 s 1186) A) Positive SSIMS spectrum, 3 s B) Positive SSIMS spectnim. 5 s C) Negative SSIMS spectrum. 3 s D) Negative SSIMS spectrum. 5 s...

Figure 55. Positive SSIMS spectra from each side of the metal-paint interface on a hot-dip galvanized steel surface after accelerated cyclic corrosion testing [1871 A) Metal B) Paint...

SSIMS has been applied by van Oou et al. [187] to study of the interfaces in a paint-metal system both quadrupole and TOP SSIMS were employed, as well as XPS. Figure 55from their paper shows the positive SSIMS spectra from the metal (Fig. 55 A) and paint (Fig. 55 B) sides of an interface exposed by soaking samples in A-methylpyrrolidone, which removes the paint by swelling but does not attack it chemically. The metal surface had been phosphate treated before paint application. Both spectra are identified... 

Figure 56. Positive SSIMS spectra from PTFE [188] A) Untreated B) 0.5-min oxygen plasma treatment C) 15-min oxygen plasma treatment...

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