Isotopes of titanium
Naturally occurring titanium is composed of five stable isotopes; 46Ti, 47Ti, 48Ti, 49Ti and 50Ti with 48Ti being the most abundant. Twenty-three radioisotopes have been characterized, with the most stable being 44Ti with a half-life of 59.1 years and 45Ti with a half-life of 184.8 minutes. All of the remaining radioactive isotopes have half-lives that are less than 10 minutes, and the majority of these have half-lives that are less than one second.
The isotopes of titanium range from 39Ti to 64Ti. The primary decay mode for isotopes lighter than the stable isotopes is β+ and the primary mode for the heavier ones is β−; the decay products are respectively scandium isotopes and vanadium isotopes.
There are two stable isotopes of titanium with an odd number of nucleons, 47Ti and 49Ti, which thus have non-zero nuclear spin of 5/2− and 7/2− and are NMR-active.
Titanium-44
Titanium-44 is a radioactive isotope of titanium that undergoes electron capture with a half-life of 59.1 years to an excited state of scandium-44, before reaching the ground state of 44Sc and ultimately of 44Ca. Because titanium-44 can decay only through electron capture, its half-life increases slowly with its ionization state and it becomes stable in its fully ionized state, though as astrophysical environments never lack electrons completely, it will always decay.Titanium-44 is produced in relative abundance in the alpha process in stellar nucleosynthesis and the early stages of supernova explosions. It is produced when stable calcium-40 adds an alpha particle, as nickel-56 is the result of adding three more. The age of supernova remnants may be determined through measurements of gamma-ray emissions from the relatively long-lived titanium-44 and of its abundance. It was observed in the Cassiopeia A supernova remnant and SN 1987A at a relatively high concentration, enhanced by the delayed decay in the ionizing conditions.