X-ray absorption experiments were performed at BL16B2
in SPring-8, one of the largest synchrotron facilities in the
world, with the approval of the Japan Synchrotron
Radiation Research Institute (JASRI) under proposal Nos.
2007B5430, 2008B5431, and 2009B5430. X-rays from the
bending magnet were monochromatized by Si(111) doublecrystal monochromator, and then focused onto the samples
by a rhodium-coated bent-cylindrical mirror. The mirror
also eliminates higher harmonics. This configuration
enables us to deliver about 1×10
10
photons/s into the area of
2mm×2mm at the sample position. The photon energies
were calibrated at Cu–K absorption edge by measuring a
copper foil. The samples were set in a conversion electron
yield (CEY) detector filled with He at the normal pressure,
and the total electron yields excited by the impinging Xrays were detected. Incident photon flux was monitored just
before the CEY chamber by a 17 cm long ion chamber
filled with N2 at the normal pressure.
The weight of copper in the deposits on the insulating
paper was quantitatively examined by X-ray fluorescence
analysis (XRF). The weight of copper sulfide in the
deposits was estimated by the weight of the sulfur in them
as follows.
(1) Sulfur in the deposits was subjected to combustion to be
transformed into sulfur dioxide (SO2) by a furnace.
(2) Sulfur dioxide was collected into absorption bottle
containing hydrogen peroxide solution.
(3) Sulfate ions formed in the hydrogen peroxide solutions
were quantitatively examined with ion chromatography
(IC) to calculate the weight of sulfur in the deposits.
Also, the weight of copper sulfide in the deposits on the
copper strip was estimated by the method similar to the
deposits on the insulating paper