Department of Earth Sciences at the University of Rome Radiocarbon Dates I

Abstract

We report here, in part, dates measured on samples from Italy since the construction of a new 14 C lab in 1990 for research in the fields of geology, paleomorphology and the biogeochemical cycle of carbon. We use liquid scintillation counting (LSC), following sample conversion to benzene through the four classical chemical steps: 1) combustion or hydrolysis to CO 2 ; 2) production of Li 2 C 2 ; 3) hydrolysis to C 2 H 2 ; 4) trimerization of acetylene to C 6 H 6 with specific catalysts. The vacuum line for benzene synthesis has been designed following a comparative review of the literature (Tamers 1960; Noakes et al. 1963; Scharpenseel & Pietig 1970; Harkness & Wilson 1973; Polach, Gower & Fraser 1972; Gupta & Polach 1985), and the valuable suggestions of many colleagues from well-established labs abroad. The compact vacuum line is mostly modular with “O”-ring-joined components, and is equipped with greaseless stopcocks. We use commercial two-stage rotary pumps, pressure transducers and gauges; an electrovalve coupled with a pressure control unit supplies the purified oxygen for sample combustion while holding constant, just higher than 1 atm, the gas pressure inside the combustion tube.