Carbon supported PtNi nanoparticles were prepared by hydrazine reduction of Pt and Ni precursor salts under different conditions, namely by conventional heating (PtNi-1), by prolonged reaction at room temperature (PtNi-2) and by microwave assisted reduction (PtNi-3). The nanocomposites were characterized by XRD, EDX, XPS and TEM and used as electrocatalysts in direct methanol fuel cell (DMFC) reactions. Investigations into the mechanism of PtNi nanoparticle formation revealed that platinum nanoparticle seeding was essential for the formation of the bimetallic nanoparticles. The average particle size of PtNi prepared by microwave irradiation was the lowest, in the range of 2.9-5.8 nm. The relative rates of electrooxidation of methanol at room temperature as measured by cyclic voltammetry showed an inverse relationship between catalytic activity and particle size in the following order PtNi-1 v PtNi-2 v PtNi-3.

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The 71Pig Rydberg state of Na2 correlating with the separated atom limit Na(3s) + Na(5p) has been observed using high-resolution cw optical-optical double resonance spectroscopy. A total of 104 identified rovibrational levels in the range v = 0-12 and 11

We present detailed investigations of our previously reported observations of the 3(1)Delta(g) and 4(1)Delta(g) Rydberg states having separated-atom limits of Na(3s) + Na(4d) and Na(3s) + Na(4f), respectively, of Na(2) using high-resolution cw optical-optical double resonance spectroscopic measurements and analyzing the assigned rovibrational energy levels both by the individual linear fit method and the Dunham polynomial fit method. We have sorted out e/f-parity observed energy levels, and then from the Dunham polynomial fits of the e-parity levels, we have derived molecular constants and constructed Rydberg-Klein-Rees potentials of the 3(1)Delta(g) and 4(1)Delta(g) states, which appear to be twin states with an avoided crossing at R(c) = 4.10 A and a splitting of DeltaE(c) = 94 cm(-1). The potentials are in good agreement with the ab initio calculations and linear fit results. The Lambda-doubling splittings and the (f-d) l-mixing are investigated. A detailed discussion is focused on the adiabatic interaction of the perturbed molecular wave functions/states causing mutual amplitude/intensity sharing giving rise to avoided crossing between the 3(1)Delta(g) and 4(1)Delta(g) states.