On revealing the vertical structure of nanoparticle films with elemental resolution: A total external reflection X-ray standing waves study

Zargham, Ardalan; Schmidt, Thomas; Flege, Jan Ingo; Sauerbrey, Marc; Hildebrand, Radowan; Röhe, Sarah; Bäumer, Marcus; Falta, J.

doi:10.1016/j.nimb.2009.09.029

Cited by 3 publications

(2 citation statements)

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“…This very first interpretation of X-ray diffraction given in 1912 by M. von Laue, was established about twenty years later by Kossel using electron excitation of a crystal, leading to the observation of the so-called Kossel lines. 2 Different ionizing radiations can be used to generate Kossel lines: 3 -electrons from an electron gun, 4-7 a scanning electron microscope 8 or a transmission electron microscope; 9 -X-ray photons from an X-ray tube, 10-12 a plasma source 13 or synchrotron radiation; [14][15][16][17][18] this case is analogous to the X-ray standing wave (XSW) technique 17 19 20 used to study the interfaces of multilayers 21 or X-ray waveguides 22 as well as thin surface films; 23 -rapid charged particles (proton or ion beam) from an accelerator. [24][25][26][27][28][29][30] In order to diffract X-rays the periodic medium can be a crystal 2 31 or a multilayer made of a periodic alternation of two or more nanometer-thick thin films.…”

Section: Introductionmentioning

confidence: 99%

Kossel Effect in Periodic Multilayers

Guen

André

et al. 2019

j nanosci nanotechnol

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The Kossel effect is the diffraction by a periodically structured medium, of the characteristic X-ray radiation emitted by the atoms of the medium. We show that multilayers designed for X-ray optics applications are convenient periodic systems to use in order to produce the Kossel effect, modulating the intensity emitted by the sample in a narrow angular range defined by the Bragg angle. We also show that excitation can be done by using photons (X-rays), electrons or protons (or charged particles), under near normal or grazing incident geometries, which makes the method relatively easy to implement. The main constraint comes from the angular resolution necessary for the detection of the emitted radiation. This leads to small solid angles of detection and long acquisition times to collect data with sufficient statistical significance. Provided this difficulty is overcome, the comparison or fit of the experimental Kossel curves, i.e., the angular distributions of the intensity of an emitted radiation of one of the element of the periodic stack, with the simulated curves enables getting information on the depth distribution of the elements throughout the multilayer. Thus the same kind of information obtained from the more widespread method of X-ray standing wave induced fluorescence used to characterize stacks of nanometer period, can be obtained using the Kossel effect.

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Section: Introductionmentioning

confidence: 99%

Kossel Effect in Periodic Multilayers

Guen

André

et al. 2019

j nanosci nanotechnol

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“… Electrons from an electron gun [3][4][5][6] or a scanning electron microscope [7];  X-ray photons from an x-ray tube [8][9][10] or synchrotron radiation [11][12][13][14]; this case is analogous to the x-ray standing wave technique [14,15] used to study the interfaces of multilayers [16] or x-ray waveguides [17] as well as superficial thin films [18];  Rapid charged particles (proton or ion beam) from an accelerator [19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Kossel interferences of proton-induced X-ray emission lines in periodic multilayers

Guen

André

et al. 2016

Nuclear Instruments and Methods in Physics Research Section B:

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The Kossel interferences generated by characteristic x-ray lines produced inside a periodic multilayer have been observed upon proton irradiation, by submitting a Cr/B 4 C/Sc multilayer stack to 2 MeV protons and observing the intensity of the Sc and Cr K characteristic emissions as a function of the detection angle. When this angle is close to the Bragg angle corresponding to the emission wavelength and period of the multilayer, an oscillation of the measured intensity is detected. The results are in good agreement with a model based on the reciprocity theorem. The combination of the Kossel measurements and their simulation, will be a useful tool to obtain a good description of the multilayer stack and thus to study nanometer-thick layers and their interfaces.  X-ray photons from an x-ray tube [8][9][10] or synchrotron radiation [11][12][13][14]; this case is analogous to the x-ray standing wave technique [14,15] The technique requires a periodic structure to diffract the emitted radiation, thus it has been applied to study crystals and interferential multilayers. However, to the best of our knowledge, Kossel lines have never been observed in multilayers upon particle excitation. It is the aim of this paper to show that it is possible to study multilayers having a nanoscale period upon proton irradiation through the observation of Kossel lines. Experimental detailsThe multilayer used for this experiment was a Cr/B 4 C/Sc periodic multilayer, whose period was repeated 100 times. The samples were deposited by magnetron sputtering onto a silicon substrate. The thickness of the Cr, B 4 C and Sc layers are 0.60, 0.20 and 0.92 nm respectively, as deduced from x-ray reflectivity (XRR) measurements in the hard and soft xray ranges. Thus the period of the stack is 1.72 nm. Other reflectivity measurements also showed that Cr atoms are present inside the B 4 C layers [26]. The thin B 4 C barrier layers were introduced to prevent the interdiffusion between Cr and Sc layers and can also improve the thermal stability of the stack [27]. The multilayer was capped with a 2.5 nm-thick B 4 C layer in order to prevent it from oxidation. Working with this Cr/B 4 C/Sc multilayer enabled us to measure well-resolved Sc and Cr K lines and to detect them at reasonable grazing angles.Indeed, this kind of short-period multilayer is chosen for microscopy or spectroscopy applications in the water window range [28,29] and requires well defined layers. Possible evolution of the multilayer composition was monitored simultaneously via the elastically backscattered protons detected in a passivated implanted planar silicon (PIPS) detector, placed at 165° with respect to the direction of the proton beam. We present in Figure 1 the spectrum so obtained for a total proton dose of 600 µC. Protons scattered from the Cr and Sc atoms appear in the peak near 1800 keV. The area of this peak was monitored, and did not change during the measurements, indicating no measurable loss of matter induced by the beam. As a further precaution, the proton beam ...

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