IN SITU SPUTTER-INITIATED RESONANCE IONIZATION MICROPROBE ANALYSIS OF ISOTOPIC COMPOSITIONS AND ELEMENTAL ABUNDANCES FOR GEOCHEMISTRY AND COSMOCHEMISTRY

RESEARCHERS ARE DEMONSTRATING THE POTENTIAL APPLICABILITY OF THE SPUTTER-INITIATED RESONANCE IONIZATION MICROPROBE (SIRIMP) TECHNIQUE FOR GEOLOGICAL STUDIES BY MEASURING PB ISOTOPE RATIOS AND U/PB ATOMIC RATIOS IN GEOLOGICAL SAMPLES RELEVANT TO GEOCHRONOLOGY. SIRIMP IS BASED ON THE CONCEPT OF RESONANCE IONIZATION OF SPUTTERED ATOMS AND POTENTIALLY OFFERS SEVERAL ADVANTAGES OVER CONVENTIONAL HIGH-RESOLUTION ION MICROPROBE INSTRUMENTS. THE MOST IMPORTANT OF THESE ARE THE HIGH SELECTIVITY, SIGNIFICANT REDUCTION OF ISOBARIC INTERFERENCES AND MATRIX EFFECTS, AND NOTABLE REDUCTION IN INSTRUMENT COST. PRELIMINARY RESEARCH IS REQUIRED IN ORDER TO (1) ASSESS INTERFERENCES DUE TO UNSUPPRESSED IONS CREATED IN THE SPUTTERING PROCESS (SECONDARY IONS) AND THOSE CREATED BY NONRESONANT PHOTOIONIZATION AND EVALUATE METHODS FOR THEIR ELIMINATION, AND (2) EXPERIMENTALLY IDENTIFY AND EVALUATE RESONANT IONIZATION SCHEMES FOR PB AND U. RESULTS FROM THE RESEARCH PROVIDE THE BASIS FOR THE DEVELOPMENT OF NEW STATE-OF-THE-ART ANALYTICAL METHODS WHICH WOULD SIGNIFICANTLY ADVANCE ANALYTICAL CAPABILITIES IN EARTH SCIENCES AND PROMOTE NEW AREAS OF RESEARCH. THESE BENEFITS COULD EXTEND TO OTHER AREAS SUCH AS THE SEMICONDUCTOR INDUSTRY, THE BIOMEDICAL FIELD, AND ENVIRONMENTAL SCIENCES.