Determination of sulphur and copper depth distribution in patina layers using nuclear reaction techniques

A method for Cu and S profiling: in patina layers was developed by applying a combination of nuclear reaction analysis (NRA) and Rutherford backscatte ring spectroscopy (RBS). The copper profiling was performed by using the 13 27 keV gamma-ray deexciting the third excited state to the ground state of Cu-63 produced by the reaction Cu-63(p, p'gamma)Cu-63. For the determinatio n of sulphur the 2230 keV gamma-ray was used deexciting the first excited s tate to the ground state of S-32 formed through the reaction S-32(p, p'gamm a)S-32, which exhibits three sharp resonances at projectile energies 3.094, 3.195 and 3.379 MeV. The relevant cross-sections were measured in the ener gy range between 3.0 and 3.7 MeV in steps of 20 keV at 125 degrees to the i ncident proton beam direction. The technique was tested using artificially produced and natural copper patina layers. Supporting information on the de pth distribution of the constituent elements of the patina samples was obta ined by p-RBS (E-p: 1.5 MeV, theta: 160 degrees). (C) 2000 Elsevier Science B.V. All rights reserved.