New directions in carbon-14 dating

Recent methods of measuring the abundance of 14C by laser enrichment coupled with charge-changing mass spectrometry promise to extend the useful range of carbon dating two or three times and to use much smaller samples for the purpose. The possibility of enrichment of 14C content in small samples by amounts in excess of 100 by laser photolysis of formaldehyde is examined and work already carried out on obtaining quantitative, high resolution absorption spectra for formaldehyde discussed. The use of cyclotrons and Van de Graaff accelerators to accelerate carbon ions for dating purposes is considered. The proposed Oxford Van de Graaff mass spectrometer which will be dedicated to 14C measurements is described. (UK)