Isotope-ratio mass spectrometry isotopic make up of the sample is obtained. For example, carbon isotope ratios are measured relative to the international standard for C. The C standard is produced from a fossil belemnite found in the Peedee Formation, which is a limestone formed in the Cretaceous period in South Carolina, U.S.A. The fossil is referred to as VPDB (Vienna Pee Dee Belemnite) and has C:C ratio of 0.0112372. Oxygen isotope ratios are measured relative the standard, V-SMOW (Vienna Standard Mean Ocean Water). It is critical that the sample be processed before entering the mass spectrometer so that only a single chemical species
Isotopes of moscovium Isotopes of moscovium Moscovium (Mc) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was Mc in 2004. There are four known radioisotopes from Mc to Mc. The longest-lived isotope is Mc with a half-life of 0.8 seconds. The table below contains various combinations of targets and projectiles which could be used to form compound nuclei with Z=115. Each entry is a combination for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with