MEASUREMENT OF CHEMICAL STATE CHANGE OF PHOSPHORUS DURING MEV-PROTON IRRADIATION BY A HIGH-RESOLUTION WAVELENGTH-DISPERSIVE PIXE SYSTEM

Abstract

Chemical state changes of phosphorus induced by proton irradiation were measured by a high-resolution wavelength-dispersive (WD) PIXE system. Six standard samples of phosphorus with different chemical states ( Ca ( H 2 PO 4)2• H 2 O ( P 5+), CaHPO 4•2 H 2 O ( P 5+), NaH 2 PO 4 ( P 5+), CaHPO 3• H 2 O ( P 3+), Ca ( H 2 PO 2)2 ( P 1+), and NaH 2 PO 2• H 2 O ( P 1+)) were prepared for the measurements. The P - K α1 peak energy for the sample of P 3+ increased after the irradiation. The peak energy of the P 3+ sample became nearly same as that of P 5+ after irradiation with more than 2 ×107 Gy . This result indicates that P 3+ in the sample has changed to P 5+ due to proton irradiation. On the other hand, the P - K α X-ray spectra for the samples of P 5+ didn't show any interesting changes even for much higher proton dose (3.4 × 108 Gy ). Also, P - K α peaks which correspond to chemical states ( P 5+ and P 3-) other than original state were observed for the sample of P 1+ in the region of more than 107 Gy .