Abstract
effective tool in analyzing the surface of inorganic salts. The goal of this project was to apply the concept of coincidence counting in SIMS for the purpose of extracting structural information along with stoichiometric data. This approach requires event-by-event bombardment and detection, which in turn is only feasible with an effective primary ion. Polyatomic projectiles are attractive in this respect since they generate enhanced secondary ion yield in comparison to monatomic projectiles at equal velocities. Because of the type of projectile used, e.g. [] , [] , this type of SIMS is referred to as C us Additionally, a time-of-flight (ToF) spectrometer was used for effective detection and identification of the secondary ions. The sodium nitrite and nitrate aspect of this study was a preliminary investigation into the primary projectile selection in order to optimize the conditions to run the phosphate growth study. A comparison of various primary ions including Cs, [], [] source. The chemistry induced by the varying projectiles was also studied. The growth of calcium phosphate on a Tina surface was also monitored. The method of preparation in this study was an attempt to mimic the growth pattern of bone in a biological system. Theoretically, as the length of exposure to a calcium phosphate solution increased, growth of the calcium phosphate on the metal surface also increased. The SI mass spectrum of the resulting metal surface showed peaks for [] and [] , representing the presence of phosphate on the surface of the sample. By monitoring the yield of the [] and [] peaks in the spectrum of various exposure times, it was possible to monitor the growth of phosphates on the [] surface. This study also focused on characterizing the phase of calcium phosphate using the [] obtained from the SI yield. Six known calcium phosphate phases, previously characterized using X-ray diffraction (XRD), were analyzed using cluster-SIMS to determine their respective [] ratio. The [] ratio of the phosphate-exposed samples was determined in order to analyze the phase of the calcium phosphate during the biomineralization process.
Justes, Dina Rodal (1998). Characterization of nitrate and phosphate surfaces using ToF-cluster SIMS. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1998 -THESIS -J87.