Physics:Isotopes of chromium

Short description: Nuclides with atomic number of 24 but with different mass numbers

Naturally occurring chromium (₂₄Cr) is composed of four stable isotopes; ⁵⁰Cr, ⁵²Cr, ⁵³Cr, and ⁵⁴Cr with ⁵²Cr being the most abundant (83.789% natural abundance). ⁵⁰Cr is suspected of decaying by β⁺β⁺ to ⁵⁰Ti with a half-life of (more than) 1.8×10¹⁷ years. Twenty-two radioisotopes, all of which are entirely synthetic, have been characterized, the most stable being ⁵¹Cr with a half-life of 27.7 days. All of the remaining radioactive isotopes have half-lives that are less than 24 hours and the majority of these have half-lives that are less than 1 minute. This element also has two meta states, ^45mCr, the more stable one, and ^59mCr, the least stable isotope or isomer.

⁵³Cr is the radiogenic decay product of ⁵³Mn. Chromium isotopic contents are typically combined with manganese isotopic contents and have found application in isotope geology. Mn-Cr isotope ratios reinforce the evidence from ²⁶Al and ¹⁰⁷Pd for the early history of the Solar System. Variations in ⁵³Cr/⁵²Cr and Mn/Cr ratios from several meteorites indicate an initial ⁵³Mn/⁵⁵Mn ratio that suggests Mn-Cr isotope systematics must result from in-situ decay of ⁵³Mn in differentiated planetary bodies. Hence ⁵³Cr provides additional evidence for nucleosynthetic processes immediately before coalescence of the Solar System. The same isotope is preferentially involved in certain leaching reactions, thereby allowing its abundance in seawater sediments to be used as a proxy for atmospheric oxygen concentrations.

The isotopes of chromium range from ⁴²Cr to ⁷⁰Cr. The primary decay mode before the most abundant stable isotope, ⁵²Cr, is electron capture and the primary mode after is beta decay.

List of isotopes

Nuclide	Z	N	Isotopic mass (u)	Half-life	Decay mode	Daughter isotope	Spin and parity	Physics:Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
42Cr	24	18	42.00643(32)#	14(3) ms [13(+4-2) ms]	β+ (>99.9%)	42V	0+
					2p (<.1%)	40Ti
43Cr	24	19	42.99771(24)#	21.6(7) ms	β+ (71%)	43V	(3/2+)
					β+, p (23%)	42Ti
					β+, 2p (6%)	41Sc
					β+, α (<.1%)	39Sc
44Cr	24	20	43.98555(5)#	54(4) ms [53(+4-3) ms]	β+ (93%)	44V	0+
					β+, p (7%)	43Ti
45Cr	24	21	44.97964(54)	50(6) ms	β+ (73%)	45V	7/2−#
					β+, p (27%)	44Ti
45mCr	50(100)# keV			1# ms	IT	45Cr	3/2+#
					β+	45V
46Cr	24	22	45.968359(21)	0.26(6) s	β+	46V	0+
47Cr	24	23	46.962900(15)	500(15) ms	β+	47V	3/2−
48Cr	24	24	47.954032(8)	21.56(3) h	β+	48V	0+
49Cr	24	25	48.9513357(26)	42.3(1) min	β+	49V	5/2−
50Cr	24	26	49.9460442(11)	Observationally Stable			0+	0.04345(13)	0.04294–0.04345
51Cr	24	27	50.9447674(11)	27.7025(24) d	EC	51V	7/2−
52Cr	24	28	51.9405075(8)	Stable			0+	0.83789(18)	0.83762–0.83790
53Cr	24	29	52.9406494(8)	Stable			3/2−	0.09501(17)	0.09501–0.09553
54Cr	24	30	53.9388804(8)	Stable			0+	0.02365(7)	0.02365–0.02391
55Cr	24	31	54.9408397(8)	3.497(3) min	β−	55Mn	3/2−
56Cr	24	32	55.9406531(20)	5.94(10) min	β−	56Mn	0+
57Cr	24	33	56.943613(2)	21.1(10) s	β−	57Mn	(3/2−)
58Cr	24	34	57.94435(22)	7.0(3) s	β−	58Mn	0+
59Cr	24	35	58.94859(26)	460(50) ms	β−	59Mn	5/2−#
59mCr	503.0(17) keV			96(20) µs			(9/2+)
60Cr	24	36	59.95008(23)	560(60) ms	β−	60Mn	0+
61Cr	24	37	60.95472(27)	261(15) ms	β− (>99.9%)	61Mn	5/2−#
					β−, n (<.1%)	60Mn
62Cr	24	38	61.95661(36)	199(9) ms	β− (>99.9%)	62Mn	0+
					β−, n	61Mn
63Cr	24	39	62.96186(32)#	129(2) ms	β−	63Mn	(1/2−)#
					β−, n	62Mn
64Cr	24	40	63.96441(43)#	43(1) ms	β−	64Mn	0+
65Cr	24	41	64.97016(54)#	27(3) ms	β−	65Mn	(1/2−)#
66Cr	24	42	65.97338(64)#	10(6) ms	β−	66Mn	0+
67Cr	24	43	66.97955(75)#	10# ms [>300 ns]	β−	67Mn	1/2−#
24	44	67.98316(54)#	10# ms (>620 ns)	β−?	68Mn	0+
				β−, n?	67Mn
				β−, 2n?	66Mn
69Cr	24	45	68.98966(54)#	6# ms (>620 ns)	β−?	69Mn	7/2+#
					β−, n?	68Mn
					β−, 2n?	67Mn
70Cr	24	46	69.99395(64)#	6# ms (>620 ns)	β−?	70Mn	0+
					β−, n?	69Mn
					β−, 2n?	68Mn

Chromium-51

Chromium-51 is a synthetic radioactive isotope of chromium having a half-life of 27.7 days and decaying by electron capture with emission of gamma rays (0.32 MeV); it is used to label red blood cells for measurement of mass or volume, survival time, and sequestration studies, for the diagnosis of gastrointestinal bleeding, and to label platelets to study their survival. It has a role as a radioactive label. Chromium Cr-51 has been used as a radioactive label for decades. It is used as a diagnostic radiopharmaceutical agent in nephrology to determine glomerular filtration rate, and in hematology to determine red blood cell volume or mass, study the red blood cell survival time and evaluate blood loss.

External links

• Chromium isotopes data from The Berkeley Laboratory Isotopes Project's

References

• 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, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document 
• Isotopic compositions and standard atomic masses from:
  • 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. 
• 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, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document 
  • National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/. 
  • Lide, David R., ed (2004). "11. Table of the Isotopes". CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.