Synchrotron applications in wood preservation and deterioration

Abstract

Several non-intrusive synchrotron techniques are being used to detect and study wood decay. The techniques use high intensity synchrotron-generated X-rays to determine the atomic structure of materials with imaging, diffraction, and absorption. Some of the techniques are X-ray absorption near edge structure (XANES), X-ray fluorescence spectroscopy (XFS), X-ray absorption fine structure (EXAFS), and X-ray computed microtomography (XCMT). Micro-fluorescence spectroscopy was used to map the accumulation and spatial distribution of elements around hyphae at the site of decay. MicroXANES determined the valence states of metals, such as manganese and iron, during fungal colonization of wood. Microtomography was used to characterize loss of wood structural integrity. The techniques are providing information about molecular structures and compositions in the heterogeneous matrix of wood. Nondestructive methods are needed to analyze the chemistry and internal structures of wood without disturbing spatial integrity or producing structural artifacts. The methods are needed to study wood during attack by decay fungi and wood treatment with preservatives. To meet this need, we have successfully studied several systems using the X-ray facilities at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory (BNL), Upton, NY. Chemical mechanisms of fungal wood decay are dependent on transition metal redox reactions producing free radicals. Synchrotron methods are uniquely suited to detect and image metal oxidation states as probes of the decay process. The same methods have been applied to study metal-based preservatives that undergo redox reactions during fixation of wood. These methods include X-ray absorption near edge structure (XANES), X-ray fluorescence spectroscopy (XFS), extended X-ray absorption fine structure (EXAFS), and X-ray computed microtomography (XCMT). In addition to decay and preservation studies, the XCMT method has also proven to be invaluable as a tool to analyze insects and fungi that cause major diseases of forests worldwide. Microtomography was employed to study beetle structure and function, to locate fungal spores on or in beetles, to assist in identification of fungi, and to provide images depicting spatial relationships of tree-insect-fungi.

Citation

Illman, Barbara L. 2003. Synchrotron applications in wood preservation and deterioration. Wood deterioration and preservation : advances in our changing world. Washington, DC : American Chemical Society, c2003. ACS symposium series ; 845: Pages 337-345