X-ray emission energy of the characteristic L- and K-shell lines for Cu and Mo (left side) and the transitions that give rise to the emission lines (right side) (from Ref. 26).
Mo-anode x-ray spectra produced by an electron energy impact of 26 keV. With and without 30-μm Mo K-edge filtering.13
Experimental arrangement of the FE x-ray setup. (a) Target chamber. (b) Details of the FE gun.
Carbon nanopearl tip. (a) The carbon nanopearl (CNP) tip is obtained by covering a metallic tip with a layer of carbon nanopearls. (b) Carbon nanopearl emitter surface. (c) A field emission gun-SEM close view of carbon nanopearls. The carbon nanosphere diameter is ∼100 nm. (d) HRTEM image of the surface of a nanopearl. The orientation of the fringes and the FFT near the surface (inset) indicated a concentric disposition of wavy nanoflakes.
FE characteristics of CNP-FE cathode within 10−6–10−7 Torr. (a) I–V characteristics; in the inset, the linear dependence of ln(I/V 2) vs 1/V indicates a Fowler-Nordheim behavior for the FE. (b) Stability of the FE currents for intervals of time of 15–25 min; samples of stable FE currents measured for total durations more than 200 h.
X-ray spectra for Mo counter-anode and for e-impact energies between 5 and 14 keV for (a) absolute counts and (b) normalized counts.
Mo L-peak monochromaticity and intensity in function of E e , for the same FE current of 5.5 μA. The solid (blue) line for the L-peak intensity is a curve fitting with a function proportional to ((E e /2.52 keV) – 1)1.67.
Evolution of the Mo L-peak for E e constant vs. 3 different e-beam currents. The centroïd of the peaks is pinned at 2.32 keV with an M value ∼71%.
Outermost L-shell emission lines26 and assumed centroïd of the merged L-peak with minimum values for the FWHM for different counter-anode materials. λ is the wavelength corresponding to the L-peak.
L-shell emission lines26 and the assumed centroïds corresponding to two distinct L α -peak and L β -peak, for different counter-anode materials. λ is the wavelength corresponding to the L-peak.
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