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The review is devoted to the application of time-of-flight secondary ion mass spectrometry (ToF-SIMS) to the analysis of biological tissues and cells. The invention of cluster primary ions significantly improved the sensitivity, especially in the mass range above several hundred of Daltons, which opened up the study of lipids, amino acids, nucleic acids, metabolites, and drugs. As other methods based on the bombardment of sample surface with a particle beam, ToF-SIMS measurements are carried out under ultrahigh vacuum conditions, which makes sample preparation of biological materials a critical stage of the experiment. Several techniques have been developed for preparing single cells, cell cultures, and tissues for the analysis. Most of them are based on conventional techniques used in histology and cytology, including optical, electron, probe microscopy and electron probe microanalysis. However, the analytical features of ToF-SIMS make it necessary to adapt these techniques. A universal solution does not exist, and the main objective of this review was to systematize and compare the developed techniques of the sample preparation for ToF-SIMS. The effect of instrumental factors on the results of the ToF-SIMS analysis of biological samples was also reported., Author(s): A. A. Gulin [sup.1] [sup.2], V. A. Nadtochenko [sup.1] [sup.2], V. N. Pogorelova [sup.3], M. Ya. Melnikov [sup.2], A. G. Pogorelov [sup.3] Author Affiliations: (1) grid.4886.2, 0000 0001 2192 [...]

The nature of radical cations stabilized in irradiated frozen 1,3-butadiene diepoxide/CF3CCl3 solutions was determined via low-temperature UV/Vis spectroscopy, electron paramagnetic resonance spectroscopy, and quantum chemistry. It was found that the cyclic radical cations yielded as radiolysis products undergo C–C bond cleavage in both oxirane cycles under the action of light with further elimination of molecular formaldehyde resulting in distonic •CH2OC+CH2 radical cations. [ABSTRACT FROM AUTHOR]

The nature of frontier molecular orbitals in complexes of phthalocyanines with p-, d0-, and d10-elements (magnesium, zinc, aluminum, gallium, and silicon) has been established by means of quantum chemical calculations. The results of the calculations prove that the highest occupied molecular orbital and the lowest unoccupied molecular orbital in the p-, d0-, and d10-complexes are localized on the macrocyclic ligands and do not involve the central cation. [ABSTRACT FROM AUTHOR]

The aim of the research was to test the advantages of spin probe electron paramagnetic resonance approach in studying polymers impregnation with organic molecules in supercritical CO2 (scCO2) The impregnation of bisphenol A polycarbonate with the spin probe TEMPOL was carried out at 307-343 K and 11.6-35 MPa. The mean and local concentrations of the spin probe in the polymer were evaluated. An increase in temperature and pressure resulted in a more even distribution of the dopant in the polymer matrix. It was observed that, at 307 K and 19.6 MPa, the spin probe was located only near the surface of the sample. Local mobility of the spin probe molecules was found to be similar in polycarbonate films impregnated in scCO2 and cast from dichloroethane solution. It was shown that changes in the structure of the surface and bulk of the polymer detected by the atomic force and optical polarization microscopy are not directly related with the distribution of the dopant molecules and their average content in the polymer. [ABSTRACT FROM AUTHOR]

The product composition and the principles of photochemical transformations of tetrahexylammonium tetrachlorocuprate [(RH)4N+]2[CuIICl4]2− (RH = C6H13) in 2-chlorobutane at 77 K have been found out by ESR spectroscopy. It has been shown that the photolysis of [(RH)4N+]2 [CuIICl4]2− results in the formation of alkyl radicals (R⊙), presumably, anions [CuICl3]2− and organic copper(II) compounds {CuIIR}. A reduction in the quantum yield of primary photolysis products during the reaction, nonequivalence of the quantum yield of the buildup of paramagnetic photolysis products to that of [CuIICl4]2− consumption, and a decrease in the total number of paramagnetic particles in the system during the photolysis have been revealed. A photolysis mechanism involving both photochemical and thermal processes is proposed. [ABSTRACT FROM AUTHOR]