Imaging of cesium in water-containing plants using TOF-SIMS

In Fukushima, Japan, the influence of radioactive Cs on agricultural crops is attracted attention as a problem. It is urgent task of elucidating dynamics of Cs in plants for securing the decontamination plan and safety of foods. Secondary ion mass spectrometry is elemental imaging technique for micro region with high sensitivity, and therefore it is suitable for the visualization of radioactive Cs in plant. However, it is difficult to analyze the original state of plants due to the evaporation of water under the vacuum condition in the apparatus. In order to investigate the behavior of radioactive Cs in plants, a new sample preparation method and imaging technique were developed. For fixing the distribution of Cs in living plants, an instrument for rapid-freezing and cutting of a plant stem in liquid nitrogen was made. In the imaging experiment, it was successfully shown that the water (ice) was maintained in the vacuum, and Cs distribution was clearly imaged over a cross-section with a high lateral resolution.