No abstract

Rotation-tunneling analysis of the origin band in the tropolone π*←π absorption system Semiclassical molecular dynamics simulations of excited state double-proton transfer in 7-azaindole dimers

The separation of protein mixtures by capillary zone electrophoresis can be plagued by wall adsorption of the protein components, causing peak broadening and distortion. A method is presented for overcoming this problem by adding ethylene glycol to the protein sample and by choosing the running buffer and protein sample to be at different pH values and molarities. This protocol appears to work for a wide class of proteins having different molecular weights and pI values. The method has been applied to the analysis of proteins in human serum. Compared to the traditional method of agarose gel electrophoresis, the present method is more rapid and offers better resolution, suggesting its potential as a clinical diagnostic of certain disease states.

High-performance capillary electrophoresis (HPCE) with UV absorbance detection (254 nm) has been applied for analyzing intracellular free ribonucleotides. The nucleotide profiles obtained from peripheral blood lymphocytes differ from those obtained from Molt4 human leukemic cells. With a 140 mM borate buffer, pH 9.4, a nearly complete profile can be obtained in 25 min. HPCE has comparable resolution to that of high-performance liquid chromatography (HPLC) but is faster in terms of time per sample run (25 min vs 45 min) and requires much less sample (nanoliter range for HPCE vs microliter range for HPLC).

The nonlinear optical technique of Jegenerate Four-Wave Mixing (DFWM) is shown to be an effective tool for the interrogation of nascent product molecules generated during a photodissociation event. By combining an absorption-based, beam-like response with the sensitivity afforded by full resonant enhancement, this scheme provides an attractive alternative to the ubiquitous laser-induced fluorescence (LIF) methodology. DFWM spectroscopy has been used to probe the unrelaxed hydroxyl (OH) radicals formed upon 266 nm photolysis of hydrogen peroxide (HOOH), with a sub-Doppler experimental configuration enabling extraction of both scalar and vector properties. In particular, the rovibrational population distribution of the ground electronic state fragments, as well as the spatial alignment of their rotational angular momenta, have been measured. These results are compared with those obtained in previous LIE studies, thereby demonstrating the utility of four-wave mixing techniques for the quantum state-specific characterization of nascent reaction products.