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-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 66Ti. 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− (respectively) and are NMR-active.

List of isotopes

NuclideZNIsotopic mass (Da)Discovery yearHalf-lifeDecay modeDaughter isotopeSpin and parityNatural abundance (molefraction)
Excitation energyNormal proportionRange of variation
39Ti221739.00268(22)#28.5(9)msβ+, p (93.7%)38Ca3/2+#
β+ (~6.3%)39Sc
β+, 2p (?%)37K
40Ti221839.990345(73)52.4(3)msβ+, p (95.8%)39Ca0+
β+ (4.2%)40Sc
41Ti221940.983148(30)81.9(5)msβ+, p (91.1%)40Ca3/2+
β+ (8.9%)41Sc
42Ti222041.97304937(29)208.3(4)msβ+42Sc0+
43Ti222142.9685284(61)509(5)msβ+43Sc7/2−
43m1Ti313.0(10)keV11.9(3)μsIT43Ti(3/2+)
43m2Ti3066.4(10)keV556(6)nsIT43Ti(19/2−)
44Ti222243.95968994(75)59.1(3)yEC44Sc0+
45Ti222344.95812076(90)184.8(5)minβ+45Sc7/2−
45mTi36.53(15)keV3.0(2)μsIT45Ti3/2−
46Ti222445.952626356(97)Stable0+0.0825(3)
47Ti222546.951757491(85)Stable5/2−0.0744(2)
48Ti222647.947940677(79)Stable0+0.7372(3)
49Ti222748.947864391(84)Stable7/2−0.0541(2)
50Ti222849.944785622(88)Stable0+0.0518(2)
51Ti222950.94660947(52)5.76(1)minβ−51V3/2−
52Ti223051.9468835(29)1.7(1)minβ−52V0+
53Ti223152.9496707(31)32.7(9)sβ−53V(3/2)−
54Ti223253.950892(17)2.1(10)sβ−54V0+
55Ti223354.955091(31)1.3(1)sβ−55V(1/2)−
56Ti223455.95768(11)200(5)msβ−56V0+
57Ti223556.96307(22)95(8)msβ−57V5/2−#
58Ti223657.96681(20)55(6)msβ−58V0+
59Ti223758.97222(32)#28.5(19)msβ−59V5/2−#
59mTi108.5(5)keV615(11)nsIT59Ti1/2−#
60Ti223859.97628(26)22.2(16)msβ−60V0+
61Ti223960.98243(32)#15(4)msβ−61V1/2−#
61m1Ti125.0(5)keV200(28)nsIT61Ti5/2−#
61m2Ti700.1(7)keV354(69)nsIT61Ti9/2+#
62Ti224061.98690(43)#9#ms[>620ns]0+
63Ti224162.99371(54)#10#ms[>620ns]1/2−#
64Ti224263.99841(64)#5#ms[>620ns]0+
65Ti224365.00559(75)#1#ms1/2−#
66Ti22440+
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Titanium-44

Titanium-44 (44Ti) 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 (that is, having a charge of +22), 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 (helium-4), as nickel-56 is the result of adding three more. The age of supernova remnants (even though nickel-56 has died away to iron) 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.

See also

Daughter products other than titanium