Nomenclature, chemical shift

One other very important attribute of photoemitted electrons is the dependence of their kinetic energy on chemical environment of the atom from which they originate. This feature of the photoemission process is called the chemical shift of and is the basis for chemical information about the sample. In fact, this feature of the xps experiment, first observed by Siegbahn in 1958 for a copper oxide ovedayer on a copper surface, led to his original nomenclature for this technique of electron spectroscopy for chemical analysis or esca. 

NMR nomenclature. Nuclear spin properties and conventions for chemical shifts. PureAppl. Chem. 2001, 73, 1795-1818. 

R.K. Harris, E.D. Becker, S.M. Cabral de Menezes, R. Goodfellow, P. Granger, NMR nomenclature. Nuclear spin properties and conventions for chemical shifts (lUPAC Recommendations 2001), Pure Appl. Chem. 73 (2001) 1795-1818. 

Nomenclature for coupled systems in 1H NMR. The interpretation of a spectrum of a molecule with many hydrogen atoms is simplified when signals that fall into classical cases can be observed. These particular cases are usually classified with a nomenclature that uses the letters of the alphabet, chosen in relation to the chemical shift (Fig. 9.18). Protons with identical or similar chemical shifts are designated by identical letters or neighbouring letters in the alphabet (AB, ABC, A2B2, etc.), while protons with very different chemical shifts are designated by letters such as A, M and X. 

Using the Si( Al) nomenclature, these are designated Si(OAl), Si(lAl), Si(2Al), Si(3Al), and Si(4Al), respectively, and each has a characteristic chemical shift. This has been very well documented for a number of zeolite types 49,51-57 Although there has been some duplication of effort the conclusions are important, and are essentially summarized by Melchior et al.57 and Klinowski et al.5 who state that in addition to identification of the Si(wAl) species, the framework Si/Al ratios can be determined from signal intensities, thereby providing an attractive alternative method to X-ray diffrac-... 

Nomenclature for coupled systems in NMR. Spectral interpretation for a molecule with many hydrogen atoms is easier when sub-groups of signals correspond to classic situations. These particular cases are classified by means of a nomenclature using the letters of the alphabet, selected with respect to the chemical shift (Figure 15.20). Protons with the same chemical environment or chemical shift are caiied equivalent. If the chemical shifts are too little different, the protons are... 

The structural entities monitored as a function of absorbed dose and irradiation conditions are presented in Figure 1. The nomenclature for describing the various types of carbon atoms, as well as the observed chemical shifts (from an internal TMS standard), are also included. The chemical shifts observed for the H-link structure are shown in Table II. 

Figure 1. Carbon-13 NMR Chemical Shifts and Nomenclature of Structural Entities Found in Polyethylene.

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