Supplementary material (ESI) for Chemical Communications
This journal is © The Royal Society of Chemistry 2004
Supplementary Information
“Ozonized Single-walled Carbon Nanotubes Investigated using NEXAFS Spectroscopy”
The partial electron yield (PEY) signal was collected using a channeltron electron
multiplier with an adjustable entrance grid bias (EGB). A negative bias of 200 V was
applied for the current set of data to obtain high sample surface sensitivity. Data were
recorded in a UHV chamber at a resolution of at least 0.1 eV. In addition, the spectra
were amassed at room temperature with the incident beam at the magic angle of 54.7°,
relative to the sample, to remove any polarization dependence of the pi-type states on the
X-ray source. The monochromator energy scale was calibrated using the carbon K-edge
π* transition of graphite, located at 285.35 eV. For the oxygen K-edge, photon energy
calibration was performed using an oxide dip absorption feature in the IO spectrum (from
the grating) at 531.2 eV. The 531.2 eV dip was internally calibrated to the gas phase
oxygen soft x-ray absorption. For the actual data collection, the samples were pressed
onto a Cu tape and mounted on a sample bar inside a UHV chamber. To eliminate the
effect of incident beam intensity fluctuations and monochromator absorption features, the
PEY signals were normalized using the incident beam intensity obtained from the
photoemission yield of a clean gold grid.
The edge jump for the C K-edge is defined as the intensity difference at energies
before the onset of C K-edge measurements (e.g. < 280 eV) and after the transitions (e.g.
> 317 eV). These spectra have been pre- and post-edge normalized. For example, the
post-edge normalization was performed by dividing the pre-edge-jump normalized
spectra by the edge jump intensity obtained far above the K-edge, beyond 320 eV.
Supplementary material (ESI) for Chemical Communications
This journal is © The Royal Society of Chemistry 2004
Figure caption. Fitted O K-edge spectra for sidewall-oxygenated nanotubes indicating
the positions of major component peaks. Gaussians and an arctangent were used to fit the
resonances and the edge jump, respectively. Measured spectrum (green), fitted spectrum
(black) and fitted components (red) are shown. Text discussion outlines the assignments.
X-axis: incident x-ray energy in eV. Y-axis: partial electron yield (in arbitrary units).