This page contains a Flash digital edition of a book.
Advanced Chemical Analysis


from organically modifi ed montmo- rillonite. This new type of material was studied for its potential of improved mechanical, thermal, and fl ame-resistance properties [ 9 , 10 ]. For comparison of detector performance, element maps were acquired using the XFlash


a standard 30 mm² XFlash® SDD under ® FlatQUAD detector and


the same acquisition conditions at 3 kV and 220 pA beam current ( Figure 3 ). The annular detector setup was optimized here not for highest solid angle but for highest possible take-off angle. So the working distance was increased above the optimum distance for large solid angle in order to investigate deeper pores. This still led to more than 12.5 times higher input count rate: 10 kcps compared to the 0.8 kcps for the conventional 30 mm 2 SDD. Note that the result from the conventional SDD suffers from extreme shadowing effects because of the rough sample surface. Shadowing is nearly eliminated in the map acquired with the annular XFlash


microscopist to properly evaluate the distribution and embedding of the silicon-containing nano-clay particles in the polymer matrix.


® FlatQUAD, allowing the Impact micro-crater in aluminum


foil . Another fascinating analysis problem is the examination of artifi cial impact craters in aluminum foils produced in the laboratory under the collection conditions for NASA’s Stardust Mission. T e primary task of this mission was to collect dust samples of a comet and return them to Earth for analysis. In order to fi nd suitable instrumentation to analyze the precious samples from space, an analogous test experiment was created on earth [ 11 ]. Polymineralic aggregate projec- tiles were produced by aerosol impregnation of a dried slurry of olivine, diopside, and pyrrhotite powders. These projec- tiles were fired at 6.05 km s -1 from a light gas gun onto aluminum foils, forming impact micro-craters. T e generated micro-craters were analyzed using a conventional SDD at 20 kV and an annular XFlash


Compositional analysis of the deeper part of the crater was not accessible using the conventional detector setup because of shadowing eff ects. In comparison, the analysis using the annular detector shows residues of the projectile that can be clearly distinguished from the aluminum target foil across the whole fi eld of view without shadowing eff ects. Residues from the three mineral components were detected mostly in the crater interior. Silicate and sulfi de melt with fl ow texture originating from olivine (Mg-green), pyrrhotite (S-blue), and diopside (Ca-red)


® FlatQUAD at 6 kV ( Figure 4 ). 34


Figure 4 : Impact experiment producing a crater in aluminum. (a) Element map of the polymineralic projectile aggregate showing Mg (green), S (blue), and Ca (red) from olivine, diopside, and pyrrhotite, respectively. (b, c) Height map and profi le of the micro-crater in aluminum foil, generated during the test experiment. (d) Crater mapped with a conventional SDD setup at 20 kV, 3nA, 1024 × 768 pixels acquired over 15.9 hours. The deeper part of the crater is not accessible. (e) Crater map acquired using the annular XFlash ® FlatQUAD detector at 6 kV, input count rate 175 kcps, 800 × 600 pixels collected in 3.9 hours. Residues from the three minerals olivine (Mg in green), diopside (Ca in red), and pyrrotite (S in blue) appear as the three primary colors, with mixtures of diopside with pyrrhotite appearing purple and of mixtures of olivine with diopside appearing orange to yellowish green. Sample and data courtesy of A. T. Kearsley 1 , T. Salge 2,1 , P. J. Wozniakiewicz 1,3 , M. C. Price 3 , R. Terborg 2 , M. J. Burchell 3 , and M. J. Cole 1 : 1 Core Research Laboratories, Natural History Museum, London, SW7 5BD, UK; 2 Bruker Nano GmbH, Berlin, Germany, 3 School of Physical Science, University of Kent, Canterbury, CT2 7NH, UK [ 11 ].


were found. Mg-rich fragments, probably from olivine, occur as well as a few particles rich in Ca or S.


Titanium dioxide nanotubes decorated with gold


nanorods . Titanium dioxide nanotubes attract attention in biomedicine because of their biocompatibility and bioactivity. It has been shown that they can promote the adhesion and proliferation of rat-bone-marrow-derived mesenchymal stem cells and hydroxyapatite nucleation and growth. Composite materials consisting of TiO 2 nanotubes decorated with metal nanoparticles, for example, Au nanoparticles or Au nanorods, have an antibacterial eff ect that can be sustained in darkness. T is eff ect is based upon the formation of a Schottky barrier between TiO 2 and the conductive Au, which can set up a lethal reaction at the cell walls of the bacteria. T us a porous TiO 2 structure decorated with Au nanoparticles or nanorods is a promising composite material for orthopedic and dental implants [ 12 ]. Figure 5 shows the Au map of a TiO 2 nanotube material containing Au nanorods of 6 nm to 12 nm in diameter. T is Au X-ray map was acquired in 4 minutes at 5 kV acceler- ating voltage and superimposed on the SEM image. T e XFlash


® www.microscopy-today.com • 2017 March


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76