Total coincidence spectrum

The total coincidence spectrum for 138Eu decay is shown in Fig. 3. 

In addition, the 136Eu decay was investigated for a brief time. Although no gamma lines could be discerned in the singles data, the 256 keV (2+ - 0+ transition in 136Sm [LIS85]) line was observed in the total coincidence spectrum, Fig. 5. 

So if this all sounds a bit bleak, what s the good news Well, strangely, there is quite a lot. For a start, let s not forget that had the 13C nucleus been the predominant carbon isotope, the development of the whole NMR technique itself would have been held back massively and possibly even totally overlooked as proton spectra would have been too complex to interpret. Whimsical speculation aside, chemical shift prediction is far more reliable for 13C than it is for proton NMR and there are chemical shift databases available to help you that are actually very useful (see Chapter 14). This is because 13 C shifts are less prone to the effects of molecular anisotropy than proton shifts as carbon atoms are more internal to a molecule than the protons and also because as the carbon chemical shifts are spread across approximately 200 ppm of the field (as opposed to the approx. 13 ppm of the proton spectrum), the effects are proportionately less dramatic. This large range of chemical shifts also means that it is relatively unlikely that two 13C nuclei are exactly coincident, though it does happen. 

Figure 31. Oscillator strength for dissociative ionization of N2 , From Wight et al. 25 broken curves, partial oscillator strengths for three dissociative ion states, with C state dissociative only from o = 3 up, which makes total C-state spectrum approximately 10% higher than spectrum shown here. The three broken curves combined equal total spectrum and give a best fit with other data points dissociative double ionization (N + + N+) is expected to set in at 48 eV o and A, from branching ratios measured in an electron-electron coincidence experiment.171 Chain curve (N2+) from El-Sherbini and Van der Wiel.108...

The UV resonance Raman spectrum of thymine was revisited in 2007, with a slightly different approach, by Yarasi, et al. [119]. Here, the absolute UV resonance Raman cross-sections of thymine were measured and the time-dependent theory was used to experimentally determine the excited-state structural dynamics of thymine. The results indicated that the initial excited-state structural dynamics of thymine occurred along vibrational modes that are coincident with those expected from the observed photochemistry. The similarity in a DFT calculation of the photodimer transition state structure [29] with that predicted from the UV resonance Raman cross-sections demonstrates that combining experimental and computational techniques can be a powerful approach in elucidating the total excited-state dynamics, electronic and vibrational, of complex systems. 

A further aid in assigning a band is its observation in the Resonance Raman (/ / ) spectrum. In RR spectroscopy, the exiting frequency coincides with a symmetry-allowed electronic transition. In general, only the totally symmetric vibrations are therefore enhanced in the RR spectrum (c.f. Sec. 6.1). The entire RR spectrum consists only of a few bands and their overtones. In the following highly symmetric species the totally symmetric breathing modes are easily identified ... 

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