Utilization of Si wafers as a supporting material for in-vacuum PIXE analysis of aqueous solutions

The use of high pure industrial crystalline Si wafers as backing materials for PIXE elemental analysis of aqueous liquid samples has been investigated. It can potentially be applied as supporting material of liquid samples owing to its advantages being available at high purity, resistant to ion beam heating effects, unaffected by chemicals, surface easily cleanable, semi-conductor that inhibits local ion beam charging effects, durable, relatively cheap and easily prepared for liquid sample deposition. Sample preparation procedure, deposition homogeneity aspects, experimental conditions and ion beam parameters optimization have been discussed. Comprehensive verification study to perform direct PIXE measurements on reference aqueous liquid sample containing 27 elements, micropipetted on Si wafers has been implemented. A combination of minimum sample preparation procedures and specific experimental conditions applied enables simple and accurate elemental analysis. Elemental concentrations, at about 5-15% absolute accuracy and uncertainties less than 15% for most elements detected, sensitivity curves and detection limits have been determined. Advantages and limitations of using Si wafers in this investigation have been discussed. Comprehensive literature comparison with other backing materials has been reviewed.