Quantitative Solid-state NMR Research Articles

Quantitative Solid-State NMR Spectra of CO Adsorbed from Aqueous Solution onto a Commercial Electrode

In this communication we present quantitative, solid-state NMR spectra of CO adsorbed from solution onto a commercial Pt/C fuel cell electrode; the CO spectra are presented as a function of surface coverage, as modified by electrochemical oxidation of surface-bound CO. These data clearly portend the widespread application of quantitative solid-state NMR techniques for studies of practical electrochemical processes. In conclusion, we report quantitative {sup 13}C NMR spectra for CO adsorbed onto commercial Pt/C fuel cell electrodes. Each spectrum shown required approximately 14 h of instrument time to acquire; we are further optimizing both the NMR parameters and probe configuration for improved signal-to-noise ratios. The number and character of CO adsorption sites are clearly accessible via this approach; if used in conjunction with in situ potential control, the number of possible studies of potential-dependent processes appears to be vast. 6 refs., 2 figs.

Effect of RF Inhomogeneity upon Quantitative Solid-State NMR Measurements

Spin counting in solid-state NMR spectroscopy requires the use of a reference standard to calibrate the magnetization detected from the unknown material. Quantitation is performed by a direct comparison of standard and unknown peak integrals that are simultaneously acquired under conditions which account for any differing relaxation behavior. Such a straightforward analysis is complicated by RF inhomogeneity effects inherent in the designs of all commercial MAS NMR probes currently available. The implications of RF inhomogeneity effects for quantitation in both Bloch-decay and cross-polarization experiments are discussed, and experimental strategies for optimization of quantitative measurements in solid-state NMR spectroscopy are given.

Improving the reliability of quantitative solid-state 13C NMR analysis of coal

Improving the reliability of quantitative solid-state 13C NMR analysis of coal