Dynamics of fragmentation of a multicharge fullerene ion

We have studied the process of fragmentation of a molecular ion of C₆₀ fullerene, which takes place as a result of the loss of five electrons in collision with a 64-keV Ar⁶⁺ ion. The spectrum of kinetic energies of the fragment ions with a given mass, as well as the number of such ions, were determined from the shapes of lines in the mass spectrum measured using a time-of-flight analyzer. It is established that, in addition to the capture of electrons by the projectile ion, an important role in the formation of a multicharge molecular C₆₀ ion is played by additional ionization of the target molecule. It is shown for the first time that the fragmentation of fullerene molecular ions is not a single-stage process. The kinetic energies and the mass spectrum of fragment ions are determined both by the Coulomb repulsion in a multicharge fullerene ion and by the subsequent additional decay of heavy fragment ions in the course of expansion.     

Fluorescent Nanosensors Based on Colloidal Quantum Dots for the Determination of Reduced Glutathione

Measurement Techniques - A fluorescent nanosensor based on colloidal quantum dots CdSe/ZnS modified with mercaptoacetic acid to determine reduced glutathione, a non-protein compound that plays an...     

Impedance spectroscopic investigation of a Rh/YSZ catalyst under polarization

Electrochemical impedance spectra at 450–600 °C and kPa of a rhodium catalyst interfaced with yttria-stabilized-zirconia (Rh/YSZ) were compared with a model based on the mechanism of electrochemical promotion. In the proposed equivalent electric circuit, existence of an “effective” double layer at the gas-exposed catalyst surface and its potential-controlled modification via diffusion of oxygen ions between the O²⁻ conducting solid electrolyte support (YSZ) and the catalyst are represented by two additional elements: adsorption capacitance and Warburg impedance. Under positive polarization, the adsorption capacitance increases dramatically indicating reinforcement of the “effective” double layer at the catalyst/gas interface, in agreement with the observation known from electrochemical promotion practice that positive polarization of a rhodium electrode leads to rhodium oxide reduction, hence, to dramatic increase in catalytic reaction rate.