Structural Data Obtainable from Different Spectra

STRUCTURAL DATA OBTAINABLE FROM DIFFERENT SPECTRA... 

Compound (98) showed a molecular formula of C90H122O12, according with its FAB-MS and 13C-NMR spectra. Analysis of the data obtained from the H-NMR spectrum and the 2D NMR experiments, showed that (98) was an isomer of (97), with different substitution of the subunits. Its absolute configuration was determined by its CD curve. The lingkages between the units were determined to be C3-0-C2 , C4-0-C3 and C6 -0-C2 , C7 -0-C3 , respectively. According to the data obtained, the structure of (98) is showed below, and the compound was called triscutin B, Fig. (54). 

As an example of the form of the information that may be derived from a pyrolysis-MS, Figure 26 [69] shows the structure of the polycarbonate (PC) and the EI-MS spectra of pyrolysis compounds obtained by DPMS of poly(bisphenol-A-carbonate) at three different probe temperatures corresponding to the three TIC (total ion current) maxima shown in Figure 27(b) Figure 27 compares the MS-TIC curve with those obtained from thermogravimetry. (The TIC trace is the sum of the relative abundances of all the ions in each mass spectrum plotted against the time (or number of scans) in a data collection sequence [70].)... 

Fine structure. Evidently the set of term values is exactly the same as on the usual theory but the quantum numbers are different, making new transitions possible and changing the intensities of the fine structure. The hydrogen fine structiure is so obscured by the natural breadth of the lines that no information can be obtained from it, and we must turn to the spectrum of ionized helium. For Paschen s data the reader is referred to Sommerfeld, figures 89-92. The only measurements of value for the... 

As a second example of the use of the orbital idea in many-electron atoms, we consider briefly the spectra from inner-shell electrons. One very direct way of measuring the energies of these is by photoelectron spectra, as discussed in Section 1.3 (see Fig. 1.11). Table 5.1 shows the binding (ionization) energies of electrons in the occupied orbitals of Na+ and Cl-, which can be obtained from the photoelectron spectrum of solid NaCl. These data illustrate the fact that the 10 electrons in Na+ occupy the If, 2j, and 2p orbitals, and the 18 in Cl- occupy If, 2s, 2p, 3s, and 3p. Remembering that there am three different p orbitals for each n, we can see that these ions have five and nine occupied orbitals, respectively. Observations such as this provide strong evidence for the shell structure of atoms, and the principle that no more than two electrons can occupy each individual orbital. 

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