<Original>Application of SEM-EDXA Technique to the Study of Metal Distribution in Preservative-Treated Wood

Abstract

The potential and limitations of the SEM-EDXA technique for determination of the metal concentration and its distribution in the preservative-treated wood were investigated. Operating conditions such as the accelerating voltage (20 keV), the working distance (15mm), the illuminating current (200 μμA.) and the distance of the X-ray detector from the specimen were held constant throughout the entire study. Results obtained were as follows. (1) The smallest size which it was practible to analyse in the bulk specimen was in the range of 3.5-4.5 μm in diameter. Hence the different cell wall layers were not analysed as separate entities in the point analysis. (2) Acquisition time of X-rays at one point on the cell wall at most should be restricted within 200 seconds for the prevention of the heat-damage of the specimen by electron bombardment. (3) Tilting angle of the specimen affected greatly the X-ray emission. Hence, for quantitative analysis, the comparison of X-ray intensities should be restricted within the portion which take the same tilting angle. (4) The X-ray intensity increased linearly in proportion to the metal concentration in the cell wall although there was a considerable variation in analysis. (5) Minimum detection limit of Cr, Cu and Zn in the cell wall was about 0.1 w/w percent in every case.