Velaug Myrseth

Adiabatic and vertical carbon 1s ionization energies in representative small molecules

Abstract Adiabatic and vertical carbon 1s ionization energies are reported for methane (CH 4 ), ethane (CH 3 CH 3 ), ethene (CH 2 CH 2 ), ethyne (HCCH), carbon monoxide (CO), carbon dioxide (CO 2 ), fluoromethane (CH 3 F), trifluoromethane (CHF 3 ), and tetrafluoromethane (CF 4 ) with an absolute accuracy of about 0.03 eV. The results are in good agreement with earlier values but are measured with higher resolution and accuracy than has previously been available.

Xenon N4, 500 Auger spectrum - a useful calibration source

Abstract In the xenon N 4,5 OO Auger spectrum there are 19 prominent lines ranging in kinetic energy from 8 to 36 eV that provide a convenient set of standards for calibrating electron spectrometers. Combining optical data with recent measurements of this spectrum gives energies for these lines that are absolutely accurate to 11 meV. For most lines the relative accuracy is better than 1 meV; for a few it is about 3 meV. The spin–orbit splitting of the xenon 4d lines is determined to be 1979.0±0.5 meV.

Line shape and lifetime in argon 2p electron spectroscopy

Abstract The argon 2p photoelectron spectrum and the argon L3M23M23 1S0 Auger spectrum have been measured at several photon energies between 6 and 80 eV above the 2p3/2 threshold with an instrumental line width significantly smaller then the natural line width. The spectra are described well by the theory of van der Straten et al. [Z. Phys. D 8 (1988) 35] provided that allowance is made for the instrumental resolution and measurements are made at a sufficiently low pressure. The lifetime (Lorentzian) line width determined from these measurements for the core-ionized atom is 112±3 meV, in good agreement with the line width for the 2p3/2→4s core-excited state, 114±2 meV, indicating that the 4s electron has little influence on the Auger decay rate. Remeasurement of the line width for the carbon 1s hole in carbon dioxide gives values in good agreement with the previous measurement of 99 meV.

Characterization of carbon black modified by maleic acid

We present here a method for modifying the surface of carbon black (CB) using a simple heat treatment in the presence of a carboxylic acid as well as water or ethylene glycol as a solvent. CB was mixed with maleic acid and either water or ethylene glycol, and heated at 250°C. Unlike the traditional surface modification processes which use heat treatment of carbon with mineral acids the present modification method using a carboxylic acid proved to be simple and time efficient. CB from two different vendors was used, and the modified samples were characterized by TGA, BET surface area measurement, XRD, particle size and zeta potential measurements, and FTIR. It was found that several material properties, including thermal stability and surface area, of the modified CB are significantly altered relative to the parental carbon samples. This method provides a rapid and simple route to tailor new materials with desired properties.

Electron attenuation in free, neutral ethane clusters

The electron effective attenuation length (EAL) in free, neutral ethane clusters has been determined at 40 eV kinetic energy by combining carbon 1s x-ray photoelectron spectroscopy and theoretical lineshape modeling. More specifically, theory is employed to form model spectra on a grid in cluster size (N) and EAL (λ), allowing N and λ to be determined by optimizing the goodness-of-fit χ(2)(N, λ) between model and observed spectra. Experimentally, the clusters were produced in an adiabatic-expansion setup using helium as the driving gas, spanning a range of 100-600 molecules in mean cluster size. The effective attenuation length was determined to be 8.4 ± 1.9 Å, in good agreement with an independent estimate of 10 Å formed on the basis of molecular electron-scattering data and Monte Carlo simulations. The aggregation state of the clusters as well as the cluster temperature and its importance to the derived EAL value are discussed in some depth.

Effect of Temperature on the Transformation of Carbon Black into Nanotubes

In this paper, successful structural transformation of carbon black (CB) into nanotubes and nanoonion like structures at relatively low temperatures in the presence of transition metal catalyst is reported. This study focuses also on the influence of the temperature on the structural transformation of CB into nanostructures. The experiments were carried out at 700°C and 1000°C in a horizontal tube furnace under N2 atmosphere. The obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). It was found that increase in the synthesis temperature from 700°C to 1000°C influences the morphology of the produced nanotubes significantly and the degree of crystallinity also increased with the temperature..