A differential sputter yield measurement technique is described, which consists of a quartz crystal monitor that is swept at constant radial distance from a small target region where a high current density xenon ion beam is aimed. This apparatus has been used to characterize the sputtering behavior of various forms of carbon including polycrystalline graphite, pyrolytic graphite, and PVD-infilt...

We report a comparative study of optical properties of 5-20 nm thick pyrolytic carbon (PyC) films, graphite, and graphene. The complex dielectric permittivity of PyC is obtained by measuring polarization-sensitive reflectance and transmittance spectra of the PyC films deposited on silica substrate. The Lorentz-Drude model describes well the general features of the optical properties of PyC from...

A simple and highly sensitive sensor based on edge-plane pyrolytic graphite electrode (EPPGE) coated with single-wall carbon nanotubes is proposed for diclofenac determination in nanomolar concentrations. The oxidation of diclofenac occurred in two well-defined peaks having peak potentials 439 and 854 mV at pH 7.2. The modified electrode showed excellent catalytic activity presenting much highe...

Raman spectroscopy and Raman imaging were used to examine several types of carbon electrode materials, including glassy carbon (GC) and highly ordered pyrolytic graphite (HOPG). Variations in the intensity ratio of the D and E2g Raman bands across the carbon surface indicated varying carbon microstructure. The D/E2g ratio for polished GC and pyrolytic graphite edge (PG) was relatively constant,...

The electrochemical ox idation of 6-hydroxy-2,4,5-triaminopyrimidine (I) at pyrolytic graphite electrode has been studied in phosphate buffers of pH range 2.5-10.8. Under cyclic voltammetric conditions, the 2e, 2H+ ox idation of this compound is fo und to give alloxan, which has been characterized on the basis of IR, mass and NMR spectral data. The kinetics of the decay of the UV -absorbing int...

The reduction potentials of two relatively high-molecular-mass enzymes were determined directly at an edge pyrolytic graphite electrode by using square-wave voltammetry. The equilibrium reduction potential versus standard hydrogen electrode was determined for Clostridium pasteurianum hydrogenase I (E'0 = -377 +/- 10 mV; molecular mass 60 kDa) and Rhodospirillum rubrum carbon monoxide dehydrogen...

Escherichia coli endonuclease III (EndoIII) and MutY are DNA glycosylases that contain [4Fe4S] clusters and that serve to maintain the integrity of the genome after oxidative stress. Electrochemical studies on highly oriented pyrolytic graphite (HOPG) revealed that DNA binding by EndoIII leads to a large negative shift in the midpoint potential of the cluster, consistent with stabilization of t...

A comparative study of the physical adsorption of RNAse A and RNAse Bacillus pumilis onto a negatively charged surface of mica, a hydrophobic surface of pyrolytic graphite and a surface of lipid layers of dipalmitoylphosphatidylcholine (DPPC) was performed by atomic force microscopy. It was found that microbial RNAse, unlike RNAse A, 1) is adsorbed onto the negatively charged surface of mica in...