Naturally occurring titanium (22Ti) is composed of five stable isotopes; 46Ti, 47Ti, 48Ti, 49Ti and 50Ti with 48Ti being the most abundant (73.8% natural abundance). Twenty-one radioisotopes have been characterized, with the most stable being 44Ti with a half-life of 60 years, 45Ti with a half-life of 184.8 minutes, 51Ti with a half-life of 5.76 minutes, and 52Ti with a half-life of 1.7 minutes. All of the remaining radioactive isotopes have half-lives that are less than 33 seconds, and the majority of these have half-lives that are less than half a second.[1]
The isotopes of titanium range in atomic mass from 39.00 u (39Ti) to 64.00 u (64Ti). The primary decay mode for isotopes lighter than the stable isotopes (lighter than 46Ti) is β+ and the primary mode for the heavier ones (heavier than 50Ti) is β−; their respective decay products are scandium isotopes and the primary products after are vanadium isotopes.
|-| rowspan=3|39Ti| rowspan=3 style="text-align:right" | 22| rowspan=3 style="text-align:right" | 17| rowspan=3|39.00161(22)#| rowspan=3|31(4) ms
[31(+6-4) ms]| β+, p (85%)| 38Ca| rowspan=3|3/2+#| rowspan=3|| rowspan=3||-| β+ (15%)| 39Sc|-| β+, 2p (<.1%)| 37K|-| rowspan=2|40Ti| rowspan=2 style="text-align:right" | 22| rowspan=2 style="text-align:right" | 18| rowspan=2|39.99050(17)| rowspan=2|53.3(15) ms| β+ (56.99%)| 40Sc| rowspan=2|0+| rowspan=2|| rowspan=2||-| β+, p (43.01%)| 39Ca|-| rowspan=2|41Ti| rowspan=2 style="text-align:right" | 22| rowspan=2 style="text-align:right" | 19| rowspan=2|40.98315(11)#| rowspan=2|80.4(9) ms| β+, p (>99.9%)| 40Ca| rowspan=2|3/2+| rowspan=2|| rowspan=2||-| β+ (<.1%)| 41Sc|-| 42Ti| style="text-align:right" | 22| style="text-align:right" | 20| 41.973031(6)| 199(6) ms| β+| 42Sc| 0+|||-| 43Ti| style="text-align:right" | 22| style="text-align:right" | 21| 42.968522(7)| 509(5) ms| β+| 43Sc| 7/2−|||-| style="text-indent:1em" | 43m1Ti| colspan="3" style="text-indent:2em" | 313.0(10) keV| 12.6(6) μs||| (3/2+)|||-| style="text-indent:1em" | 43m2Ti| colspan="3" style="text-indent:2em" | 3066.4(10) keV| 560(6) ns||| (19/2−)|||-| 44Ti| style="text-align:right" | 22| style="text-align:right" | 22| 43.9596901(8)| 60.0(11) y| EC| 44Sc| 0+|||-| 45Ti| style="text-align:right" | 22| style="text-align:right" | 23| 44.9581256(11)| 184.8(5) min| β+| 45Sc| 7/2−|||-| 46Ti| style="text-align:right" | 22| style="text-align:right" | 24| 45.9526316(9)| colspan=3 align=center|Stable| 0+| 0.0825(3)||-| 47Ti| style="text-align:right" | 22| style="text-align:right" | 25| 46.9517631(9)| colspan=3 align=center|Stable| 5/2−| 0.0744(2)||-| 48Ti| style="text-align:right" | 22| style="text-align:right" | 26| 47.9479463(9)| colspan=3 align=center|Stable| 0+| 0.7372(3)||-| 49Ti| style="text-align:right" | 22| style="text-align:right" | 27| 48.9478700(9)| colspan=3 align=center|Stable| 7/2−| 0.0541(2)||-| 50Ti| style="text-align:right" | 22| style="text-align:right" | 28| 49.9447912(9)| colspan=3 align=center|Stable| 0+| 0.0518(2)||-| 51Ti| style="text-align:right" | 22| style="text-align:right" | 29| 50.946615(1)| 5.76(1) min| β−| 51V| 3/2−|||-| 52Ti| style="text-align:right" | 22| style="text-align:right" | 30| 51.946897(8)| 1.7(1) min| β−| 52V| 0+|||-| 53Ti| style="text-align:right" | 22| style="text-align:right" | 31| 52.94973(11)| 32.7(9) s| β−| 53V| (3/2)−|||-| 54Ti| style="text-align:right" | 22| style="text-align:right" | 32| 53.95105(13)| 1.5(4) s| β−| 54V| 0+|||-| 55Ti| style="text-align:right" | 22| style="text-align:right" | 33| 54.95527(16)| 490(90) ms| β−| 55V| 3/2−#|||-| rowspan=2|56Ti| rowspan=2 style="text-align:right" | 22| rowspan=2 style="text-align:right" | 34| rowspan=2|55.95820(21)| rowspan=2|164(24) ms| β− (>99.9%)| 56V| rowspan=2|0+| rowspan=2|| rowspan=2||-| β−, n (<.1%)| 55V|-| rowspan=2|57Ti| rowspan=2 style="text-align:right" | 22| rowspan=2 style="text-align:right" | 35| rowspan=2|56.96399(49)| rowspan=2|60(16) ms| β− (>99.9%)| 57V| rowspan=2|5/2−#| rowspan=2|| rowspan=2||-| β−, n (<.1%)| 56V|-| 58Ti| style="text-align:right" | 22| style="text-align:right" | 36| 57.96697(75)#| 54(7) ms| β−| 58V| 0+|||-| 59Ti| style="text-align:right" | 22| style="text-align:right" | 37| 58.97293(75)#| 30(3) ms| β−| 59V| (5/2−)#|||-| 60Ti| style="text-align:right" | 22| style="text-align:right" | 38| 59.97676(86)#| 22(2) ms| β−| 60V| 0+|||-| rowspan=2|61Ti| rowspan=2 style="text-align:right" | 22| rowspan=2 style="text-align:right" | 39| rowspan=2|60.98320(97)#| rowspan=2|10# ms
[>300 ns]| β−| 61V| rowspan=2|1/2−#| rowspan=2|| rowspan=2||-| β−, n| 60V|-| 62Ti| style="text-align:right" | 22| style="text-align:right" | 40| 61.98749(97)#| 10# ms||| 0+|||-| 63Ti| style="text-align:right" | 22| style="text-align:right" | 41| 62.99442(107)#| 3# ms||| 1/2−#|||-| 64Ti[2] | style="text-align:right" | 22| style="text-align:right" | 42| 63.998410(640)#| 5# ms
[>620 ns]||| 0+||
Titanium-44 (44Ti) is a radioactive isotope of titanium that undergoes electron capture to an excited state of scandium-44 with a half-life of 60 years, before the ground state of 44Sc and ultimately 44Ca are populated.[3] Because titanium-44 can only undergo electron capture, its half-life increases with ionization and it becomes stable in its fully ionized state (that is, having a charge of +22).[4]
Titanium-44 is produced in relative abundance in the alpha process in stellar nucleosynthesis and the early stages of supernova explosions.[5] It is produced when calcium-40 fuses with an alpha particle (helium-4 nucleus) in a star's high-temperature environment; the resulting 44Ti nucleus can then fuse with another alpha particle to form chromium-48. The age of supernovae may be determined through measurements of gamma-ray emissions from titanium-44 and its abundance. It was observed in the Cassiopeia A supernova remnant and SN 1987A at a relatively high concentration, a consequence of delayed decay resulting from ionizing conditions.