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 60 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)	47.867(1)[1]

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.

• 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.