Isotopes of titanium

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.[2]

Main isotopes of titanium (22Ti)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
44Ti syn 63 y ε 44Sc
γ –
46Ti 8.25% stable
47Ti 7.44% stable
48Ti 73.72% stable
49Ti 5.41% stable
50Ti 5.18% stable
Standard atomic weight Ar, standard(Ti)

The isotopes of titanium range in atomic mass from 38.01 u (38Ti) to 62.99 u (63Ti). 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.[2]

List of isotopes
Nuclide
[n 1]		 Z N Isotopic mass (Da)
[n 2][n 3]		 Half-life
[n 4]		 Decay
mode
[n 5]		 Daughter
isotope
[n 6]		 Spin and
parity
[n 7][n 4]		 Natural abundance (mole fraction)
Excitation energy Normal proportion Range of variation
38Ti 22 16 38.00977(27)# <120 ns 2p 36Ca 0+
39Ti 22 17 39.00161(22)# 31(4) ms
[31(+6-4) ms]		 β+, p (85%) 38Ca 3/2+#
β+ (15%) 39Sc
β+, 2p (<.1%) 37K
40Ti 22 18 39.99050(17) 53.3(15) ms β+ (56.99%) 40Sc 0+
β+, p (43.01%) 39Ca
41Ti 22 19 40.98315(11)# 80.4(9) ms β+, p (>99.9%) 40Ca 3/2+
β+ (<.1%) 41Sc
42Ti 22 20 41.973031(6) 199(6) ms β+ 42Sc 0+
43Ti 22 21 42.968522(7) 509(5) ms β+ 43Sc 7/2−
43m1Ti 313.0(10) keV 12.6(6) μs (3/2+)
43m2Ti 3066.4(10) keV 560(6) ns (19/2−)
44Ti 22 22 43.9596901(8) 60.0(11) y EC 44Sc 0+
45Ti 22 23 44.9581256(11) 184.8(5) min β+ 45Sc 7/2−
46Ti 22 24 45.9526316(9) Stable 0+ 0.0825(3)
47Ti 22 25 46.9517631(9) Stable 5/2− 0.0744(2)
48Ti 22 26 47.9479463(9) Stable 0+ 0.7372(3)
49Ti 22 27 48.9478700(9) Stable 7/2− 0.0541(2)
50Ti 22 28 49.9447912(9) Stable 0+ 0.0518(2)
51Ti 22 29 50.946615(1) 5.76(1) min β− 51V 3/2−
52Ti 22 30 51.946897(8) 1.7(1) min β− 52V 0+
53Ti 22 31 52.94973(11) 32.7(9) s β− 53V (3/2)−
54Ti 22 32 53.95105(13) 1.5(4) s β− 54V 0+
55Ti 22 33 54.95527(16) 490(90) ms β− 55V 3/2−#
56Ti 22 34 55.95820(21) 164(24) ms β− (>99.9%) 56V 0+
β−, n (<.1%) 55V
57Ti 22 35 56.96399(49) 60(16) ms β− (>99.9%) 57V 5/2−#
β−, n (<.1%) 56V
58Ti 22 36 57.96697(75)# 54(7) ms β− 58V 0+
59Ti 22 37 58.97293(75)# 30(3) ms β− 59V (5/2−)#
60Ti 22 38 59.97676(86)# 22(2) ms β− 60V 0+
61Ti 22 39 60.98320(97)# 10# ms
[>300 ns]		 β− 61V 1/2−#
β−, n 60V
62Ti 22 40 61.98749(97)# 10# ms 0+
63Ti 22 41 62.99442(107)# 3# ms 1/2−#
  1. mTi – Excited nuclear isomer.
  2. ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  5. Modes of decay:
    EC:Electron capture
    n:Neutron emission
    p:Proton emission
  6. Bold symbol as daughter – Daughter product is stable.
  7. ( ) spin value – Indicates spin with weak assignment arguments.

Titanium-44

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 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.[4] 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.[3][4]

References
  1. Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
  2. Barbalace, Kenneth L. (2006). "Periodic Table of Elements: Ti - Titanium". Retrieved 2006-12-26.
  3. Motizuki, Y.; Kumagai, S. (2004). "Radioactivity of the key isotope 44Ti in SN 1987A". AIP Conference Proceedings. 704 (1): 369–374. CiteSeerX 10.1.1.315.8412. doi:10.1063/1.1737130.
  4. Mochizuki, Y.; Takahashi, K.; Janka, H.-Th.; Hillebrandt, W.; Diehl, R. (2008). "Titanium-44: Its effective decay rate in young supernova remnants, and its abundance in Cas A". Astronomy and Astrophysics. 346 (3): 831–842. arXiv:astro-ph/9904378.
  5. Fryer, C.; Dimonte, G.; Ellinger, E.; Hungerford, A.; Kares, B.; Magkotsios, G.; Rockefeller, G.; Timmes, F.; Woodward, P.; Young, P. (2011). Nucleosynthesis in the Universe, Understanding 44Ti (PDF). ADTSC Science Highlights (Report). Los Alamos National Laboratory. pp. 42–43.