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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]
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−# | ||||
- ^ mTi – Excited nuclear isomer.
- ^ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
- ^ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
- ^ a b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
- ^ Modes of decay:
EC: Electron capture
n: Neutron emission p: Proton emission - ^ Bold symbol as daughter – Daughter product is stable.
- ^ ( ) 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
- ^ 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.
- ^ a b Barbalace, Kenneth L. (2006). "Periodic Table of Elements: Ti - Titanium". Retrieved 2006-12-26.
- ^ a b 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.
- ^ a b c 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.
- ^ 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.
- Isotope masses from:
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- Isotopic compositions and standard atomic masses from:
- de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683.
- Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. Lay summary.
- Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.