Scanning transmission X-ray microscopy

NEXAFS experiments on NOM can be conducted in several modes that differ in the type of detected particle and objectives of the experiment transmission (X rays transmitted through the sample), fluorescence (fluorescent X rays due to absorption of the X-ray beam), or electron yield (photo-emitted electron) (Sparks, 2003). Alternatively, the techniques can be divided into full-field applications such as transmission X-ray microscopy (TXM) and X-ray photoemission electron microscopy (PEEM), in comparison to scanning techniques such as scanning transmission X-ray microscopy (STXM) and scanning photoemission microscopy (SPEM) that provide spatial information of elemental forms. 

Brandes, J. A., Lee, C., Wakeham, S., Peterson, M., Jacobsen, C., Wirick,S., and Cody, G. (2004). Examining marine particulate organic matter at sub-micron scales using scanning transmission X-ray microscopy and carbon X-ray absorption near edge structure spectroscopy. Marine Chem. 92,107-121. 

Hitchcock, A. P., Araki, T., Ikeura-Sekiguchi, H., Iwata, N., and Tani, K. (2003). 3d chemical mapping of toners by serial section scanning transmission X-ray microscopy. J. Phys. IV 104, 509-512. 

Rothe, J., Plaschke, M., and Denecke, M. A. (2004). Scanning transmission X-ray microscopy as a speciation tool for natural organic molecules. Radiochim. Acta 92,711-715. 

Schumacher, M., Christl, I., Scheinost, A. C., Jacobsen, C., and Kretzschmar, R. (2005). Chemical heterogeneity of organic soil colloids investigated by scanning transmission X-ray microscopy and C-ls NEXAFS microspectroscopy. Environ. Sci. Technol. 39, 9094-9100. 

PMMA-POSS15 cyclopentyl-POSS) as compatibilizer, using scanning transmission X-ray microscopy (STXM) and scanning probe microscopy (SPM) methods was examined. 

Figure 1.18 (a) Schematic representation of phase-separated donor-acceptor networks and (b) scanning transmission X-ray microscopy (STXM) image of the thermally annealed (at 200°C) films of PFB/F8BT blends processed from chloroform solution, showing the nanoscale phase separation. Reprinted from [217] with permission from Wiley... 

K. B. Burke, A. J. Stapleton, B. Vaughan, X. Zhou, A. L. D. Kilcoyne, W. J. Belcher, P. C. Dastoor, Scanning Transmission X-Ray Microscopy of Polymer Nanoparticles Probing Morphology on Sub-10 Nm Length Scales. Nanotechnology 2011,22,265710. 

Burke, K.B., Stapleton, A.J., Vaughan, B Zhou, X., Kilcoyne, A.L.D., Belcher, W.J., and Dastoor, P.C. (2011) Scanning transmission X-ray microscopy of polymer nanoparticles probing morphology on sub-lOnm length scales. Nanotechnology, 22, 265710. 

Figure 7.32 Scanning transmission X-ray microscopy images of PS/PMMA (30/70) and PS/PMMA/Closite SOB (27/63/10) taken after annealing at 190 °C. Reprinted with permission from M. Si, T. Araki, H. Ade, A.L.D. Kilcoyne, R. Fisher, J.C. Sokolov, M.H. Rafailovich, Macromolecules, 2006, 39, 4793 2006, American...

Recently, several articles have appeared on the combined use of different other microanalysis techniques for atmospheric aerosols. Let us mention one. Hopkins et al. successfully used CC SEM/EDX, time-of-flight secondary ion mass spectrometry (TOF-SIMS) and scanning transmission X-ray microscopy/near-edge X-ray absorption fine structure analysis (STXM/NEXAFS) to study quantitatively methanesulphonate (CHsSOs") and non-sea salt sulphate in individual marine aerosol particles. This indicated e.g. that CHsSOs" salts were the dominant source of non-seasalt sulphur in large particles, while sulphate was more common in smaller particles. Quantitative assessment of these two forms is important for kinetic modelling concerning the pathways of natural dimethylsulphide oxidation and the impact on the number and size of cloud condensation nuclei in the marine environment. 

Felten A, Bittencourt C, Pireaux J-J, Reichelt M, Mayer J, Hernandez-Cruz D, Hitchcock AP. (2007) Individual multiwall carbon nanotubes spectroscopy by scanning transmission X-ray microscopy. Nano Lett7 1530—6984. 

Scanning transmission X-ray microscopy has been used most extensively for polymer research, e.g. for bulk characterisation of polymeric materials with chemical sensitivity at a spatial resolution of 50 nm [739], STXM has also been used for the analysis (morphology, size distributions, spatial distributions and quantitative chemical compositions) of copolymer polyol-reinforcing particles in polyurethane [740], Pitkethly [741] has reviewed the role of microscopy in the evaluation of fibre/matrix interfacial properties and micromechanical characteristics of fibre-reinforced plastic composites. 

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