Line spectrum interpretation

The EPR spectrum of the ethyl radical presented in Fig. 12.2b is readily interpreted, and the results are relevant to the distribution of unpaired electron density in the molecule. The 12-line spectrum is a triplet of quartets resulting from unequal coupling of the electron spin to the a and P protons. The two coupling constants are = 22.38 G and Op — 26.87 G and imply extensive delocalization of spin density through the a bonds Note that EPR spectra, unlike NMR and IR spectra, are displayed as the derivative of absorption rather than as absorption. 

There is more good news. Anyone who has stared at the periodic table and has taken basic chemistry knows that the orbital structure postulated for atoms is the same for all kinds of atoms. And all atoms exhibit a line spectrum that is independent of the viewer s position. So there is no reason, in principle, why you couldn t solve this problem for other sorts of atoms too. The basic ideas are indeed the same. Of course, problems arise in interpretation. For example, if we are interpreting our little electron as a wave, then what are we supposed to do with two electrons After all, a wave plus a wave is still just a wave. As near as I can tell, quantum mechanics still has a way to go before it replaces the old fashioned pictures of helium, lithium and other, more complex, atoms. And any physicist can tell you that molecules, stripped of their pretty spherical symmetry, are trouble indeed. 

Is ascribed to the 5-membered cyclic radical(III). The temperature dependence of the spectral pattern Is interpreted as restricted rotation about the C-C bond of >C-CH2 group at lower temperature and Its free rotation at higher temperature. To confirm this assignment ESR spectra of Irradiated MDMA-d4 were measured. If the 3-llne spectrum Is due to the 5-membered cyclic radical(III), the radical(VI) should be observed In the case of MDMA-d4, and Its gives a 5-line spectrum based upon the Interaction between an un-... 

The nine-line spectrum observed after irradiation of polymethylmethacrylate (PMMA) at room temperature has been the subject of much investigation and interpretation. It consists of five well-resolved narrow lines of approximately binomial distribution of intensities and four broader lines evenly distributed between the five (Fig. 14). Identical spectra are obtained at room temperature after UV irradiation or mechanical degradation [41]. A spectrum with similar general features is observed for the other methacrylic and methacrylate polymers. 

In other applications the presence of forbidden and spin flip lines makes interpretations more difficult, particularly when they occur in the same spectrum as for the malonic acid radical in Fig. 4.20. The early work by McConnell and co-workers to obtain the first ESR single crystal data of this radical, including an interpretation of the forbidden transitions must therefore be considered as an extra-ordinary... 

Studies of the TMM biradical itself began in the late sixties when Dowd observed an ESR spectrum interpretable as that of the TMM triplet species from a sample of 4-methylenepyrazoline that was photolyzed in a glassy matrix at — 196°C. Further, all six hydrogens were equivalent from the splitting of the half-field resonance line (Am = 2 transitions) thus indicating that the TMM triplet had symmetry Similar observations were made upon photolysis of 3-methylenecyclobutanone. Both reactions were claimed to produce MCP as the sole product. However, photolysis of the ketone at —ITC in butadiene gives not only MCP but... 

Zeolitic water NMR spectrum interprets the interchange of water molecules between sites and the transit time is small compared to residence time. Water molecules in larger zeolite cavities exhibit the same properties of isolated liquid, but for smaller zeolite cavities, they appear to cluster aroimd anions. During dehydration, it appears that water molecules line the inside of the zeolite super cages. Cation-dipole interactions play an important role in the nature and structure of zeolitic water... 

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