Application of the ESEM Technique in Wood Research: Part I. Optimization of Imaging Parameters and Working Conditions
Keywords:
Wood, SEM, ESEM, structure, microstructure, fractographyAbstract
A study using the ESEM (Environmental Scanning Electron Microscopy) technique was performed on wood objects in order to assess the particular advantages, possibilities, and limitations of this microscopic tool. In contrast to conventional high vacuum SEM, in ESEM specimens can be investigated in a gaseous atmosphere, usually of water vapor. This enables the observation of non-conductive, polymeric, composite, and porous materials (such as wood) in their natural state, without drying, evacuating, or sputtering them with a layer of carbon or metal. Further advantages include observations in a wide range of temperatures (-15° to 1000°C), conduction of dynamic processes such as condensation, freezing, and thawing of the specimen during observation, or mechanical testing.
The imaging quality of ESEM for natural samples, however, is inferior to that of conventional SEM, and the specimens are liable to beam damage. The process of acquiring an image in ESEM is more complex than in SEM, demanding the optimization of a number of interacting parameters. These include the physical conditions of the specimen, conditions of the chamber environment, and electronic parameters of the formation and optimization of the image.
The work on the ESEM can be performed through several operational modes that offer various sets of environmental and imaging conditions. This article presents guidance for assessment of influential operating parameters and their selection for the optimization of the ESEM work with wood.
References
Cameron, R. E., and A. M. McDonald. 1994. Minimizing sample evaporation in the environmental scanning electron microscope. J. Microscopy173, Pt 3 (March 1994): 227-237.nCraciun, R., P. D. Kamdem, and C. R. McIntyre. 1997. Characterisation of CDDC (copper dimethyl dithiocarbamate) treated wood. Holzforschung51(6):519-525.nDanilatos, G. D. 1986. Beam-radiation effects on wool in the ESEM. Pages 674-675 in Proc. 44th Annual Meeting of EMSA. San Francisco Press, San Francisco, CA.nDawson-Andoh, B., and P. D. Kamdem. 1998. Application of environmental scanning electron microscopy to the study of macrodistribution of copper in copper naphthenate treated hardwoods. Holzforschung52(6):603-606.nForsberg, P., and P. Lepoutre. 1994. Environmental scanning electron microscope examination of paper in high moisture environment: Surface structural changes and electron beam damage. Scanning Microscopy8(1):31-34.nFrühmann, K., I. Burgert, and S. Stanzl-Tschegg. 2003. Detection of the fracture path under tensile loads through in situ tests in an ESEM chamber. Holzforschung57(3):326-332.nGu, H-M., A. Zink-Sharp, and J. Sell. 2001. Hypothesis on the role of cell wall structure in differential transverse shrinkage of wood. Holz Roh-Werkst.59(5):436-442.nJohnson, R. 1996. Environmental Scanning Electron Microscopy. An introduction to ESEM. Philips Elecron Optics, Eindhoven, The Netherlands. 55 pp.nKaegi, R., and L. Holzer. 2003. Transfer of a single particle for continued ESEM and TEM analysis. Atmosph. Environ.37/31:4353-4359.nKamdem, D. P., and C. R. McIntyre. 1998. Chemical investigation of 23-year-old CDDC-treated southern pine. Wood Fiber Sci.30(1):64-71.nKamdem, D. P., J. Zhang, J., and M. Freeman. 1998. The effect of post-steaming on copper naphthenate-treated southern pine. Wood Fiber Sci.30(2):210-217.nKifetew, G., and D. Sandberg. 2000. Material damage due to electron beam during testing in the environmental scanning electron microscope (ESEM). Wood Fiber Sci.32(1):44-51.nKifetew, G., F. Thuvander, L. Berglund, and H. Lindberg. 1998. The effect of drying on wood fracture surface from specimen loaded in wet condition. Wood Sci. Technol.32:83-94.nMaldas, D. C., and D. P. Kamdem. 1998. Surface characterisation of chromated copper arsenate (CCA)-treated red maple. J. Adhesion Sci. Technol.12(7):763-772.nMott, L., S. M. Shaler, L. H. Groom, and B-H. Liang. 1995. The tensile testing of individual wood fibers using environmental scanning electron microscopy and video image analysis. TAPPI J.78(5):143-148.nMott, L., S. M. Shaler, L. H. Groom, and B-H. Liang. 1996. A technique to measure strain distributions in single wood pulp fibers. Wood Fiber Sci.28(4):429-437.nNitz, H., P. Reichert, H. Roemling, and R. Muelhaupt. 2000. Influence of compatibilizers on the surface hardness, water uptake and the mechanical properties of poly-(propiylene) wood four composites prepared by reactive extrusion. Macromol. Mater. Eng.276/277:51-58.nPulido-Novicio, L., T. Hata, Y. Kurimoto, S. Doi, S. Ishihara, and Y. Imamura. 2001. Adsorption capacities and related characteristics of wood charcoals carbonized using a one-step or two-step process. J. Wood Sci.47(1): 48-57.nRazi, P. S., A. Raman, and R. Portier. 1997. Studies on mechanical properties of wood-polymer composites. J. Compos. Mater.31(23):2391-2401.nRosenquist, M. 1999. Localization of wood improvement compounds by microautoradiography and ESEM. Holzforschung53(6):648-654.nRosenquist, M. 2001. Acetyl group distribution in acetylated wood investigated by microautoradiography. Holzforschung55(3):270-275.nSchiekel, M., A. Lindner, A. Dürichen, and P. Haller. 2002. Belastungsuntersuchungen an Holzproben im ESEM. Unpublished results (manuscript).nShaler, S. M., L. H. Groom, and L. Mott. 1996. Microscopic analysis of wood fibers using ESEM and confocal microscopy. Pages 25-32 in Proc. Woodfiber-Plastic Composites Symp., Forest Prod. Soc, Madison, WI.nSheenan, J. G., and L. E. Scriven. 1991. Assessment of environmental scanning electron microscopy for coating research. Pages 377-383 in: Proc. 1991 TAPPI Coating Boston Conference. TAPPI Press, Atlanta, GA.nSippola, M., and K. Frühmann. 2001. In situ longitudinal tensile tests of pine wood. Pages 493-501 in P. Navi, ed. Pre-proceedings of the International Conference of the European Society of Wood Mechanics. Ecole Polytechnique Federale. Lausanne, Switzerland.nStehr, J. 1999. Laser ablation of machined wood surfaces. Effect on end-grain gluing of pine (Pinus silvestris L). Holzforschung53(6):655-661.nStehr, J., and S. Oestlund. 2000. An investigation of the crack tendency on wood surfaces erent machining operations. Holzforschung54(4):427-436.nStehr, J., J. Seltman, and I. Johansson. 1998. UV laser ablation—an improved method of sample preparation for microscopy. Holzforschung52(1):1-6.nStehr, J., J. Seltman, and I. Johansson. 1999. Laser ablation of machined wood surfaces. Part 1. Effect on end-grain gluing of pine (Pinus silvestris L.) and spruce (Picea abies Karst.). Holzforschung53(1):93-103.nTurkulin, H., and J. Sell. 1997. Structural and fractographic study on weathered wood. An application of FE SEM microscopy to the "Thin strip" method. Research and work report Nr. 115/36. Swiss Federal Laboratories for Materials Testing and Research (EMPA). Dübendorf, Switzerland. 40 pp.nTurkulin, H., and J. Sell. 2002. Investigations into the photodegradation of wood using microtensile testing. Part 4: Tensile proterties and fractography of weathered wood. Holz Roh-Werkst.60(1):96-105.nTurkulin, H., L. Holzer, and J. Sell. 2004. Application of the ESEM technique in wood research. Research and work report Nr. 115/51. Swiss Federal Laboratories for Materials Testing and Research (EMPA). Dübendorf, Switzerland. 58 pp.nTurkulin, H., L. Holzer, and J. Sell., and K. Richter. 2005. Application of the ESEM technique in wood research. Part 2: Comparison of operational modes. This issue 565-573.n
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