TY - CONF A1 - Vogl, Jochen T1 - Cu project on calibration approaches for absolute isotope ratios N2 - This presentations summarizes the difficulties in the purification of enriched copper isotopes by high vacuum subimation. It shows as well thelimitations for a CCQM key comparison on this topic. T2 - CCQM Isotope Ratio Work Group Meeting CY - Bern, Switzerland DA - 09.10.2019 KW - Absolute isotope ratio KW - Isotope purification KW - Metal sublimation KW - Gravimtric isotope mixtures PY - 2019 AN - OPUS4-49518 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -