干旱区生态环境知识资源中心

A time-resolved X-ray absorption spectroscopy apparatus in the laboratory scale has been set-up which utilizes laser plasmas as a soft X-ray source. One of the major objectives using this apparatus is to observe X-ray absorption fine structures (XAFS) of various materials during materials processing in an energy region between 100eV and 3keV. For this purpose, we have provided two sets of optical and detecting systems, i.e., a toroidal mirror, grazing incidence flat-field grating and MCP for lower energy region (100-1000eV), and a toroidal mirror, curved KAP crystal arid MCP for higher energy region (1-3keV). The most intense X-rays are generated from Au plasma and the intensity reaches as high as 10(16) photons/pulse in 2pi steradian in the energy region below 300eV. In this case, the conversion efficiency of the laser energy to X-rays is 4.6%. The energy resolution of the spectrometer DELTAE/E has been found to be 5X10(-3). We show some examples of XAFS measurements on carbon during laser ablation.