Spectrometry ENDOR

Reflecting their aromaticity, porphyrins usually give strong M(Por) + and M(Por) 2+ mass peaks, though some fragmentations of the side chains and loss of the metal from labile metalloporphyrins are often observed.2 The ionization energy of M(TPP) (M = H2, Cu) was reported to be 8.0eV by mass spectrometry. MCD, CD, resonance Raman, Zeeman, ENDOR, ESR and Mossbauer spectroscopies have been reviewed in detail.2... 

About 30 years later, the pentaisopropylcydopentadienyl cation (9+) was generated from the corresponding chloride and bromide and proved to be stable in the frozen solution at 115 K, existing as a triplet [12]. Pentaisopropylcydopentadiene is unique in that it not only forms a stable anion - which is aromatic, just like any other cyclopentadienide - but also a persistent radical that has been characterized by ESR/ENDOR, 1H NMR spectroscopy, and mass spectrometry, as well as by X-ray crystal structure analysis [12]. 

The most recent mass spectrometry data using Sr to replace Ca suggests that the fast exchanging substrate site may involve interaction with Ca. This interpretation agrees with H/ H-ENDOR and ESEEM results showing that two water molecules are bound, one to a Mn site and the other to a nomnagnetic site postulated to be Ca. ... 

In the above section the photodevices that can be employed to reach the appropriate reactant state were outlined. In the remainder of the chapter, the devices and instruments for monitoring the subsequent change and determining the rate characteristics will be discussed. By far the most frequently employed diagnostic techniques are optical absorption and emission spectrometry other less-used methodologies include light-scattering spectrometry, and the electron-spin-based spectroscopies, such as EPR, ENDOR, and CIDNP. These last three are not addressed in this review. 

Table I. Electron-Nuclear Hyperfine Constants for Vitrains from Selected Coals as Determined by ENDOR Spectrometry...

The material presented herein was meant to provide an indication of the utility of ESR and ENDOR spectrometries as probes to characterize the free radicals in coals and coal-derived materials. The results suggest that, in addition to their use in characterization studies, the techniques may have potential in helping to elucidate the mechanism of coal liquefaction. They further suggest that coals may be heat-treated directly in the cavity of an ESR spectrometer with the assurance that reliable data will be obtained provided simple precautionary measures are taken to avoid unwanted effects. Similar in situ ESR measurement of coals under liquefaction conditions remains a possibility, although considerable... 

The ease of purification and remarkable stability of P. furiosus ferredoxin, together with the availability of the recombinant protein, has enabled it to become one of the best studied of all ferredoxins, with numerous investigations into the properties of both the protein and of its single [4Fe-4S] cluster. These include the use of spectroscopic techniques, such as electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), Mossbauer, mass spectrometry, and nuclear magnetic resonance (NMR). Such studies... 

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