Analytical Chemistry

Figure 9.27 Schematic diagram of a continuous wave NMR spectrometer. frequency of the transmitter. By employing a superconductin ...

covering a wide frequency range (500–1500 Hz). Following each pulse, excited nuclei return to the ground state producing a decay ...

For a proton or carbon-13 nucleus I is 1/2, hence mI can be only ± 1/2 and two energy levels, or spin states, are produced (Figu ...

Spectra of solid samples, however, consist of broad lines and are less easily interpreted. The amount of structural information ...

in frequency (Hz) relative to a standard, the universally accepted reference compound being tetramethylsilane, (CH 3 ) 4 Si (TMS ...

Figure 9.30 Approximate chemical shifts for protons in various functional groups relative to TMS. *Chemical shift is highly depe ...

Figure 9.31 Anisotropic shielding in unsaturated groups. (Shielding zones +; deshielding zones –). (a) Ethyne. (b) Ethene. (c) E ...

Spin-spin Coupling Absorption bands arising from adjacent protons are split into multiplet peaks by a mutual interaction of the ...

between the component peaks of each doublet is the same and is known as the coupling constant JAX usually measured in Hz. It sho ...

between the coupled groups is large compared to the coupling constant, i.e. ∆ν/J> ~ 7. As this ratio becomes smaller, the inn ...

Figure 9.34 Progressive distortions as A 2 X 2 →A 2 B 2 in the configuration ZCH 2 CH 2 Y, 60 MHz. ...

Figure 9.35 Splitting diagram for an AMX system. 3,5-octanedionato)europium(III) (Eu(dpm) 3 and Eu(fod) 3 and Eu(fod) 3 respecti ...

Figure 9.36 (a) 60 MHz proton NMR spectrum of n-hexanol. (b) 100 MHz proton NMR spectrum of n-hexanol with 0.29 mole equivalents ...

done using a partial decoupling technique known as off-resonance decoupling which allows only the coupling between^13 C nuclei a ...

Figure 9.38 (^13) C chemical shift ranges (ppm from TMS). Extended ranges sometimes occur when polar substituents are attached t ...

Figure 9.40 (^13) C spectrum of 3-hydroxymethylbenzene (noise decoupled). Pulsed Fourier Transform NMR (FT-NMR) Conventional sca ...

Figure 9.41 (a) Single decaying sine wave and a plot of the single frequency it represents. (b) two decaying sine waves and a pl ...

Pulsed FT-NMR has facilitated the study of nuclei other than^1 H where the sensitivity obtainable from a CW instrument is totall ...

Figure 9.42 (a) Generalized multipulse sequence for 1-D or 2-D NMR. (b) Generation of a 2-D NMR spectrum S( f 1 , f 2 ). (^13) C ...

due to the methyls, methylenes and methines have been assigned. A set of DEPT spectra for ethyl benzoate is shown in Figure 9.43 ...