X max sdd

High-resolution imaging and chemical analysis took place in the FEI HeliosNanolab 650 scanning electron microscope (SEM) using energy-dispersive X-ray spectroscopy (EDS) (Hillsboro, OR, USA). All the samples were coated with an approximately 10 nm carbon layer to prevent the charging effects of a biological specimen during electron irradiation. The EDS spectra were collected with the following experimental parameters: electron acceleration voltage (15 kV), electron current (200 pA) and chamber vacuum (10⁻⁶ hPa). Under such conditions, we achieved an energy resolution of 145 eV at Mn Kα line and elemental sensitivity of approximately 0.01 wt% (X-Max SDD, Oxford Instruments, Abington, UK).

Samples of selenite-amended culture were treated and analyzed as previously described (25 (link)). The samples were examined in an FEI Tecnai F20 field emission gun (FEG) transmission electron microscope operating at 200 kV and fitted with a Gatan Orius SC600A charge-coupled-device (CCD) camera, an Oxford Instruments XMax SDD energy-dispersive X-ray (EDX) detector, and a high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) detector.
For thin-section analysis, after the ethanol dehydration steps, the cells were embedded in EMbed 812 epoxy resin and cut into thin sections (90 nm, using a diamond knife on a Reichert Ultracut S ultramicrotome). The sections were supported on copper grids and coated with carbon. TEM specimen holders were cleaned by plasma prior to TEM analysis to minimize contamination. Samples were examined with a high-resolution Philips CM 200 transmission electron microscope at an acceleration voltage of 200 kV under standard operating conditions with the liquid nitrogen anticontaminator in place.

Energy dispersive X-ray spectroscopy (EDS) was carried out with a JEOL JSM-7001F field emission scanning electron microscope (Tokyo, Japan) and an X-Max SDD (silicon drift detector) from Oxford Instruments (Abingdon, UK).
Energy dispersive X-ray fluorescence (EDF) was carried out in a helium atmosphere with a Panalytical Epsilon 3XL (Royston, U.K.) equipped with an X-ray tube containing an Ag anode. The C₆₀ powder was in the first instance deposited on a Prolene membrane. For quantitative measurements, a suspension of 0.955 g L⁻¹ of C₆₀ in demineralized water was deposited in quantities of 20 µL (representing 19.1 µg of C₆₀) on a polycarbonate membrane. The measurement was carried out after complete evaporation of the water. A control containing only demineralized water was analyzed too.