Near-surface structural phase transition of SrTiO3 studied with zero-field beta-detected nuclear spin relaxation and resonance

We demonstrate that zero-field beta-detected nuclear quadrupole resonance and spin relaxation of low energy (8)Li can be used as a sensitive local probe of structural phase transitions near a surface. We find that the transition near the surface of a SrTiO(3) single crystal occurs at T(c) approximately 150K, i.e., approximately 45K higher than T(c)bulk, and that the tetragonal domains formed below T(c) are randomly oriented.     

Eine elektrophoretische Analyse von Proteinextrakten normaler und dystrophischer Schafsmuskeln

Ohne Zusammenfassung     

Single-scan longitudinal relaxation measurements in high-resolution NMR spectroscopy

Several single-scan experiments for the measurement of the longitudinal relaxation time (T1) are proposed. These experiments result in fast and accurate determinations of the relaxation rate, are relatively robust to pulse imperfections, and preserve information about the chemical shift. The method used in these experiments is to first encode the T1 values as a spatial variation of the magnetization and then to read out this variation either by applying a weak gradient during acquisition or by sequentially observing different slices of the sample. As a result, it is possible to reduce the time necessary to determine the T1 values by one or two orders of magnitude. This time saving comes at the expense of the signal-to-noise level of the resulting spectrum and some chemical shift resolution.     

Broadband proton-decoupled proton spectra

We present a new method for recording broadband proton-decoupled proton spectra with absorption mode lineshapes and substantially correct integrals; in both these respects, the new method has significant advantages over conventional J-spectroscopy. In our approach, the decoupled spectrum is simply obtained from the 45 degrees projection of the diagonal-peak multiplets of an anti z-COSY spectrum. This method is straightforward to apply, and does not require any unusual data processing. However, there is a significant reduction in sensitivity when compared to a conventional proton spectrum. The method is demonstrated for typical medium-sized molecules, and it is also shown how such a decoupled spectrum can be used to advantage in measurements of diffusion constants (DOSY), the measurement of relaxation parameters, and the analysis of complex mixtures.     

Mechanistic insights into electrocatalytic reactions provided by SERS

In situ vibrational spectroscopy can provide molecular-level mechanistic insights missing from purely electrochemical measurements. Surface enhanced Raman spectroscopy (SERS) is a particularly promising method and is used in aqueous and nonaqueous studies of a variety of electrode reactions. Enhancement of the weak Raman signal is achieved by structuring the electrode surface or by use of SERS probes. This review article highlights the recent use of SERS to study several important electrode reactions: oxygen reduction and evolution, carbon monoxide oxidation and carbon dioxide reduction and the electrocatalytic oxidation of small organic molecules such as formic acid.     

One-Dimensional NOE Experiments Using Pulsed Field Gradients

Previously, it has been shown that the use of pulsed field gradients in one-dimensional NOE experiments results in spectra of much higher quality than it has previously been possible to record. Such high-quality spectra make it possible to measure, with complete confidence, very small NOE enhancements and also make it straightforward to measure NOE buildup curves. In this paper, the spin dynamics behind these NOE experiments with gradients are analyzed in detail; the effects of strong coupling and molecular diffusion are also examined. It is also shown how the basic experiments can be improved upon, in particular how unwanted anti-phase contributions (SPT effects) can be eliminated entirely. Experimental illustrations of the various methods and improvements are given and practical recommendations made as to how the experiments are best performed.