• 14C Measurements of Sub-Milligram Carbon Samples from Aerosols

      Weissenbök, Roland; Biegalski, Steven R.; Currie, Lloyd A.; Klinedinst, Donna B.; Golser, Robin; Klouda, George A.; Kutschera, Walter; Priller, Alfred; Rom, Werner; Steier, Peter; et al. (Department of Geosciences, The University of Arizona, 1998-01-01)
      Accelerator mass spectrometry (AMS) at the milligram level is routinely performed, but it is difficult to go substantially below 100 micrograms of carbon. We discuss various approaches for sample preparation, machine operation and data evaluation, to meet the special requirements of 14C AMS measurements at the microgram-carbon level. Furthermore, we present first results obtained at the Vienna Environmental Research Accelerator (VERA) from 14C measurements of a snow sample from Gaithersburg, Maryland, USA, prepared at the National Institute of Standards and Technology (NIST).
    • First 14C Results from Archaeological and Forensic Studies at the Vienna Environmental Research Accelerator

      Wild, Eva; Golser, Robin; Hille, Peter; Kutschera, Walter; Priller, Alfred; Puchegger, Stephan; Rom, Werner; Steier, Peter; Vycudilik, W. (Department of Geosciences, The University of Arizona, 1998-01-01)
      14C dating with the new Vienna Environmental Research Accelerator (VERA) began with the age determination of a mummified marmot found in the Austrian Alpine region. Soft tissue and bones of the marmot were used for the investigation. For comparison, bone material from known-age samples was also processed and measured. These exercises showed that 14C dating with VERA is reliable, and since that time various samples from archaeological context have been dated. We also studied the applicability of the 14C method in forensic sciences to determine the time of death of human individuals. 14C/ 12C measurements of samples from different organic human material (bone collagen, lipids from bone and bone marrow, hair) were performed and compared with the tropospheric "bomb peak" values to transform the measured ratios into "calibrated ages". For specific substances with rapid turnover rates, this gives an estimate for the time of death of the individual. In our study, lipids and hair yield reasonable times of death, whereas the collagen fraction from bones, which has a relatively long turnover time, is not suitable for this purpose.
    • Systematic Investigations of 14C Measurements at the Vienna Environmental Research Accelerator

      Rom, Werner; Golser, Robin; Kutschera, Walter; Priller, Alfred; Steier, Peter; Wild, Eva (Department of Geosciences, The University of Arizona, 1998-01-01)
      A newly operating accelerator mass spectrometry (AMS) facility such as VERA has to go through an extensive testing phase in order to establish optimal conditions for 14C measurements, especially in the field of archaeological samples where an overall precision of 0.5% is desirable. We discuss the results of our measurements at the milligram carbon level as they relate to long-term stability, reproducibility, precision and isotope fractionation.