Isotopes of lawrencium

Isotopes of lawrencium (₁₀₃Lr)
β+	256No
β+	260No
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Lawrencium (₁₀₃Lr) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized was ²⁵⁸Lr in 1961. There are fourteen known isotopes from ²⁵¹Lr to ²⁶⁶Lr, except ²⁶³Lr and ²⁶⁵Lr, and seven isomers. The longest-lived known isotope is ²⁶⁶Lr with a half-life of 11 hours.

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da) ^{[n 2]}^{[n 3]}	Half-life	Decay mode ^{[n 4]}	Daughter isotope	Spin and parity ^{[n 5]}^{[n 6]}
Nuclide ^{[n 1]}	Excitation energy^{[n 6]}			Half-life	Decay mode ^{[n 4]}	Daughter isotope	Spin and parity ^{[n 5]}^{[n 6]}
²⁵¹Lr^[3]	103	148	251.09418(32)#	24.4+7.0 −4.5 ms	α	²⁴⁷Md	7/2−
²⁵¹Lr^[3]	103	148	251.09418(32)#	24.4+7.0 −4.5 ms	SF^[4]^{[n 7]}	(various)	7/2−
^251mLr^[3]	117(27) keV			42+42 −14 ms	α	²⁴⁷Md	1/2−
²⁵²Lr^{[n 8]}^[1]	103	149	252.09526(26)#	369(75) ms [0.36+0.11 −0.07 s]	α (~98%)	²⁴⁸Md
					SF (~2%)	(various)
					β⁺?	²⁵²No
²⁵³Lr	103	150	253.09509(22)#	632(46) ms^[1]	α (>97%)	²⁴⁹Md	(7/2−)
					SF (1.0%)	(various)
					β⁺ (<2%)	²⁵³No
^253mLr	30(100)# keV			1.32(14) s	α (>86%)	²⁴⁹Md	(1/2−)
					SF (12%)	(various)
					β⁺ (<2%)	²⁵³No
²⁵⁴Lr^[1]^[5]	103	151	254.096240(100)^[6]	11.9(9) s	α (71.7%)	²⁵⁰Md	(4+)
					β⁺ (28.3%)	²⁵⁴No
					SF (<0.1%)	(various)
^254mLr	110(6) keV^[7]			20.3(4.2) s	α	²⁵⁰Md	(1-)
					β⁺	²⁵⁴No
					IT?	²⁵⁴Lr
²⁵⁵Lr^[1]	103	152	255.096562(19)	31.1(1.1) s	α (85%)	²⁵¹Md	1/2−^[3]
					β⁺ (15%)^[8]	²⁵⁵No
					SF (rare)	(various)
^255m1Lr^[1]	32(2) keV^[7]			2.54(5) s	IT (~60%)	²⁵⁵Lr	(7/2−)
^255m1Lr^[1]	32(2) keV^[7]			2.54(5) s	α (~40%)	²⁵¹Md	(7/2−)
^255m2Lr^[1]	796(12) keV			<1 μs	IT	^255m1Lr	(15/2+)
^255m3Lr^[1]	1465(12) keV			1.78(0.05) ms	IT	^255m2Lr	(25/2+)
²⁵⁶Lr^[1]	103	153	256.09849(9)	27.9(1.0) s	α (85%)	²⁵²Md	(0-,3-)#
					β⁺ (15%)	²⁵⁶No
					SF (<0.03%)	(various)
²⁵⁷Lr^[9]	103	154	257.09942(5)#	1.24+0.85 −0.36 s	α	²⁵³Md	(9/2+,7/2-)
					β⁺ (rare)	²⁵⁷No
					SF (rare)	(various)
^257mLr^[1]	100(50)# keV			200+160 −60 ms	α	²⁵³Md	(1/2−)
^257mLr^[1]	100(50)# keV			200+160 −60 ms	IT	²⁵⁷Lr	(1/2−)
²⁵⁸Lr^[10]	103	155	258.10176(11)#	3.54+0.46 −0.36 s	α (97.4%)	²⁵⁴Md
²⁵⁸Lr^[10]	103	155	258.10176(11)#	3.54+0.46 −0.36 s	β⁺ (2.6%)	²⁵⁸No
²⁵⁹Lr^[1]	103	156	259.10290(8)#	6.2(3) s	α (78%)	²⁵⁵Md	1/2-#
					SF (22%)	(various)
					β⁺ (rare)	²⁵⁹No
²⁶⁰Lr^[1]	103	157	260.10551(13)#	3.0(5) min	α (80%)	²⁵⁶Md
					β⁺ (20%)	²⁶⁰No
					SF (rare)	(various)
²⁶¹Lr^[1]	103	158	261.10688(22)#	39(12) min	SF	(various)	1/2-#
²⁶¹Lr^[1]	103	158	261.10688(22)#	39(12) min	α (<10%)^[11]	²⁵⁷Md	1/2-#
²⁶²Lr^[1]	103	159	262.10961(22)#	~4 h	β⁺	²⁶²No
					SF (<10%)	(various)
					α (<7.5%)^[11]	²⁵⁸Md
²⁶⁴Lr^{[n 9]}	103	161	264.11420(47)#	4.8+2.2 −1.3 h^[2]	SF	(various)
²⁶⁶Lr^{[n 10]}	103	163	266.11983(56)#	22(14) h [11+21 −5 h]^[1]	SF	(various)
This table header & footer: view

^ ^mLr – 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).
^ Modes of decay:

SF: Spontaneous fission
^ ( ) spin value – Indicates spin with weak assignment arguments.
^ ^a ^b # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
^ The experiment in which alpha decay of two ²⁵¹Lr states was reported did not take into account spontaneous fission branches.^[3]
^ Not directly synthesized, occurs as a decay product of ²⁵⁶Db
^ Not directly synthesized, occurs as a decay product of ²⁸⁸Mc
^ Not directly synthesized, occurs as a decay product of ²⁹⁴Ts

Nucleosynthesis

Cold fusion

²⁰⁵Tl(⁵⁰Ti,xn)^255−xLr (x=2)

This reaction was studied in a series of experiments in 1976 by Yuri Oganessian and his team at the FLNR. Evidence was provided for the formation of ²⁵³Lr in the 2n exit channel. In 2022, two states (²⁵³Lr and ^253mLr) were found.

²⁰³Tl(⁵⁰Ti,xn)^253−xLr (x=2)

This reaction was studied in a series of experiments in 1976 by Yuri Oganessian and his team at the FLNR. In 2022, two states (²⁵¹Lr and ^251mLr) were found.

²⁰⁸Pb(⁴⁸Ti,pxn)^255−xLr (x=1?)

This reaction was reported in 1984 by Yuri Oganessian at the FLNR. The team was able to detect decays of ²⁴⁶Cf, a descendant of ²⁵⁴Lr.

²⁰⁸Pb(⁴⁵Sc,xn)^253−xLr

This reaction was studied in a series of experiments in 1976 by Yuri Oganessian and his team at the FLNR. Results are not readily available.

²⁰⁹Bi(⁴⁸Ca,xn)^257−xLr (x=2)

This reaction has been used to study the spectroscopic properties of ²⁵⁵Lr. The team at GANIL used the reaction in 2003 and the team at the FLNR used it between 2004–2006 to provide further information for the decay scheme of ²⁵⁵Lr. The work provided evidence for an isomeric level in ²⁵⁵Lr.

Hot fusion

²⁴³Am(¹⁸O,xn)^261−xLr (x=5)

This reaction was first studied in 1965 by the team at the FLNR. They were able to detect activity with a characteristic decay of 45 seconds, which was assigned to²⁵⁶Lr or ²⁵⁷Lr. Later work suggests an assignment to ²⁵⁶Lr. Further studies in 1968 produced an 8.35–8.60 MeV alpha activity with a half-life of 35 seconds. This activity was also initially assigned to ²⁵⁶Lr or ²⁵⁷Lr and later to solely ²⁵⁶Lr.

²⁴³Am(¹⁶O,xn)^259−xLr (x=4)

This reaction was studied in 1970 by the team at the FLNR. They were able to detect an 8.38 MeV alpha activity with a half-life of 20s. This was assigned to²⁵⁵Lr.

²⁴⁸Cm(¹⁵N,xn)^263−xLr (x=3,4,5)

This reaction was studied in 1971 by the team at the LBNL in their large study of lawrencium isotopes. They were able to assign alpha activities to²⁶⁰Lr,²⁵⁹Lr and ²⁵⁸Lr from the 3-5n exit channels.

²⁴⁸Cm(¹⁸O,pxn)^265−xLr (x=3,4)

This reaction was studied in 1988 at the LBNL in order to assess the possibility of producing ²⁶²Lr and ²⁶¹Lr without using the exotic ²⁵⁴Es target. It was also used to attempt to measure an electron capture (EC) branch in ^261mRf from the 5n exit channel. After extraction of the Lr(III) component, they were able to measure the spontaneous fission of ²⁶¹Lr with an improved half-life of 44 minutes. The production cross-section was 700 pb. On this basis, a 14% electron capture branch was calculated if this isotope was produced via the 5n channel rather than the p4n channel. A lower bombarding energy (93 MeV c.f. 97 MeV) was then used to measure the production of ²⁶²Lr in the p3n channel. The isotope was successfully detected and a yield of 240 pb was measured. The yield was lower than expected compared to the p4n channel. However, the results were judged to indicate that the ²⁶¹Lr was most likely produced by a p3n channel and an upper limit of 14% for the electron capture branch of ^261mRf was therefore suggested.

²⁴⁶Cm(¹⁴N,xn)^260−xLr (x=3?)

This reaction was studied briefly in 1958 at the LBNL using an enriched ²⁴⁴Cm target (5% ²⁴⁶Cm). They observed a ~9 MeV alpha activity with a half-life of ~0.25 seconds. Later results suggest a tentative assignment to ²⁵⁷Lr from the 3n channel

²⁴⁴Cm(¹⁴N,xn)^258−xLr

This reaction was studied briefly in 1958 at the LBNL using an enriched ²⁴⁴Cm target (5% ²⁴⁶Cm). They observed a ~9 MeV alpha activity with a half-life of ~0.25s. Later results suggest a tentative assignment to ²⁵⁷Lr from the 3n channel with the ²⁴⁶Cm component. No activities assigned to reaction with the ²⁴⁴Cm component have been reported.

²⁴⁹Bk(¹⁸O,αxn)^263−xLr (x=3)

This reaction was studied in 1971 by the team at the LBNL in their large study of lawrencium isotopes. They were able to detect an activity assigned to ²⁶⁰Lr. The reaction was further studied in 1988 to study the aqueous chemistry of lawrencium. A total of 23 alpha decays were measured for ²⁶⁰Lr, with a mean energy of 8.03 MeV and an improved half-life of 2.7 minutes. The calculated cross-section was 8.7 nb.

²⁵²Cf(¹¹B,xn)^263−xLr (x=5,7??)

This reaction was first studied in 1961 at the University of California by Albert Ghiorso by using a californium target (52% ²⁵²Cf). They observed three alpha activities of 8.6, 8.4 and 8.2 MeV, with half-lives of about 8 and 15 seconds, respectively. The 8.6 MeV activity was tentatively assigned to ²⁵⁷Lr. Later results suggest a reassignment to ²⁵⁸Lr, resulting from the 5n exit channel. The 8.4 MeV activity was also assigned to ²⁵⁷Lr. Later results suggest a reassignment to ²⁵⁶Lr. This is most likely from the 33% ²⁵⁰Cf component in the target rather than from the 7n channel. The 8.2 MeV was subsequently associated with nobelium.

²⁵²Cf(¹⁰B,xn)^262−xLr (x=4,6)

This reaction was first studied in 1961 at the University of California by Albert Ghiorso by using a californium target (52% ²⁵²Cf). They observed three alpha activities of 8.6, 8.4 and 8.2 MeV, with half-lives of about 8 and 15 seconds, respectively. The 8.6 MeV activity was tentatively assigned to ²⁵⁷Lr. Later results suggest a reassignment to ²⁵⁸Lr. The 8.4 MeV activity was also assigned to ²⁵⁷Lr. Later results suggest a reassignment to ²⁵⁶Lr. The 8.2 MeV was subsequently associated with nobelium.

²⁵⁰Cf(¹⁴N,αxn)^260−xLr (x=3)

This reaction was studied in 1971 at the LBNL. They were able to identify a 0.7s alpha activity with two alpha lines at 8.87 and 8.82 MeV. This was assigned to²⁵⁷Lr.

²⁴⁹Cf(¹¹B,xn)^260−xLr (x=4)

This reaction was first studied in 1970 at the LBNL in an attempt to study the aqueous chemistry of lawrencium. They were able to measure a Lr³⁺ activity. The reaction was repeated in 1976 at Oak Ridge and 26s ²⁵⁶Lr was confirmed by measurement of coincident X-rays.

²⁴⁹Cf(¹²C,pxn)^260−xLr (x=2)

This reaction was studied in 1971 by the team at the LBNL. They were able to detect an activity assigned to ²⁵⁸Lr from the p2n channel.

²⁴⁹Cf(¹⁵N,αxn)^260−xLr (x=2,3)

This reaction was studied in 1971 by the team at the LBNL. They were able to detect an activities assigned to ²⁵⁸Lr and ²⁵⁷Lr from the α2n and α3n and channels. The reaction was repeated in 1976 at Oak Ridge and the synthesis of ²⁵⁸Lr was confirmed.

²⁵⁴Es + ²²Ne – transfer

This reaction was studied in 1987 at the LLNL. They were able to detect new spontaneous fission (SF) activities assigned to ²⁶¹Lr and ²⁶²Lr, resulting from transfer from the ²²Ne nuclei to the ²⁵⁴Es target. In addition, a 5 ms SF activity was detected in delayed coincidence with nobelium K-shell X-rays and was assigned to ²⁶²No, resulting from the electron capture of ²⁶²Lr.

Decay products

Isotopes of lawrencium have also been identified in the decay of heavier elements. Observations to date are summarised in the table below:

List of lawrencium isotopes produced as other nuclei decay products
Parent nuclide	Observed lawrencium isotope
²⁹⁴Ts, ²⁹⁰Mc, ²⁸⁶Nh, ²⁸²Rg, ²⁷⁸Mt, ²⁷⁴Bh, ²⁷⁰Db	²⁶⁶Lr
²⁸⁸Mc, ²⁸⁴Nh, ²⁸⁰Rg, ²⁷⁶Mt, ²⁷²Bh, ²⁶⁸Db	²⁶⁴Lr
²⁶⁷Bh, ²⁶³Db	²⁵⁹Lr
²⁷⁸Nh, ²⁷⁴Rg, ²⁷⁰Mt, ²⁶⁶Bh, ²⁶²Db	²⁵⁸Lr
²⁶¹Db	²⁵⁷Lr
²⁷²Rg, ²⁶⁸Mt, ²⁶⁴Bh, ²⁶⁰Db	²⁵⁶Lr
²⁵⁹Db	²⁵⁵Lr
²⁶⁶Mt, ²⁶²Bh, ²⁵⁸Db	²⁵⁴Lr
²⁶¹Bh, ²⁵⁷Db^g,m	²⁵³Lr^g,m
²⁶⁰Bh, ²⁵⁶Db	²⁵²Lr
²⁵⁵Db	²⁵¹Lr

Isotopes

Summary of all lawrencium isotopes known
Isotope	Year discovered	discovery reaction
²⁵¹Lr^g	2005	²⁰⁹Bi(⁴⁸Ti,2n)
²⁵¹Lr^m	2022	²⁰³Tl(⁵⁰Ti,2n)
²⁵²Lr	2001	²⁰⁹Bi(⁵⁰Ti,3n)
²⁵³Lr^g	1985	²⁰⁹Bi(⁵⁰Ti,2n)
²⁵³Lr^m	2001	²⁰⁹Bi(⁵⁰Ti,2n)
²⁵⁴Lr^g	1985	²⁰⁹Bi(⁵⁰Ti,n)
²⁵⁴Lr^m	2019
²⁵⁵Lr^g	1970	²⁴³Am(¹⁶O,4n)
²⁵⁵Lr^m1	2006
²⁵⁵Lr^m2	2009
²⁵⁵Lr^m3	2008
²⁵⁶Lr	1961? 1965? 1968? 1971	²⁵²Cf(¹⁰B,6n)
²⁵⁷Lr^g	1958? 1971	²⁴⁹Cf(¹⁵N,α3n)
²⁵⁷Lr^m	2018
²⁵⁸Lr	1961? 1971	²⁴⁹Cf(¹⁵N,α2n)
²⁵⁹Lr	1971	²⁴⁸Cm(¹⁵N,4n)
²⁶⁰Lr	1971	²⁴⁸Cm(¹⁵N,3n)
²⁶¹Lr	1987	²⁵⁴Es + ²²Ne
²⁶²Lr	1987	²⁵⁴Es + ²²Ne
²⁶⁴Lr	2020	²⁴³Am(⁴⁸Ca,6α3n)
²⁶⁶Lr	2014	²⁴⁹Bk(⁴⁸Ca,7α3n)

Fourteen isotopes of lawrencium plus seven isomers have been synthesized with ²⁶⁶Lr being the longest-lived and the heaviest, with a half-life of 11 hours. ²⁵¹Lr is the lightest isotope of lawrencium to be produced to date.

Lawrencium-253 isomers

A study of the decay properties of ²⁵⁷Db (see dubnium) in 2001 by Hessberger et al. at the GSI provided some data for the decay of ²⁵³Lr. Analysis of the data indicated the population of an isomeric level in ²⁵³Lr from the decay of the corresponding isomer in ²⁵⁷Db. The ground state was assigned spin and parity of 7/2−, decaying by emission of an 8794 keV alpha particle with a half-life of 0.57 s. The isomeric level was assigned spin and parity of 1/2−, decaying by emission of an 8722 keV alpha particle with a half-life of 1.49 s.

Lawrencium-255 isomers

Recent work on the spectroscopy of ²⁵⁵Lr formed in the reaction ²⁰⁹Bi(⁴⁸Ca,2n)²⁵⁵Lr has provided evidence for an isomeric level.

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
^ ^a ^b Oganessian, Yu. Ts.; Utyonkov, V. K.; Kovrizhnykh, N. D.; et al. (2022). "New isotope ²⁸⁶Mc produced in the ²⁴³Am+⁴⁸Ca reaction". Physical Review C. 106 (064306). doi:10.1103/PhysRevC.106.064306.
^ ^a ^b ^c ^d Huang, T.; Seweryniak, D.; Back, B. B.; et al. (2022). "Discovery of the new isotope ²⁵¹Lr: Impact of the hexacontetrapole deformation on single-proton orbital energies near the Z = 100 deformed shell gap". Physical Review C. 106 (L061301). doi:10.1103/PhysRevC.106.L061301. S2CID 254300224.
^ Leppänen, A.-P. (2005). Alpha-decay and decay-tagging studies of heavy elements using the RITU separator (PDF) (Thesis). University of Jyväskylä. pp. 83–100. ISBN 978-951-39-3162-9. ISSN 0075-465X.
^ Vostinar, M.; Heßberger, F. P.; Ackermann, D.; Andel, B.; Antalic, S.; Block, M.; Droese, Ch.; Even, J.; Heinz, S.; Kalaninova, Z.; Kojouharov, I.; Laatiaoui, M.; Mistry, A. K.; Piot, J.; Savajols, H. (14 February 2019). "Alpha-gamma decay studies of 258Db and its (grand)daughter nuclei 254Lr and 250Md". The European Physical Journal A. 55 (2): 17. Bibcode:2019EPJA...55...17V. doi:10.1140/epja/i2019-12701-y. ISSN 1434-601X. S2CID 254115080. Retrieved 3 July 2023.
^ Meng Wang; et al. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references". Chinese Physics C. 45 (3): 030003. Bibcode:2021ChPhC..45c0003W. doi:10.1088/1674-1137/abddaf. S2CID 235282522.
^ ^a ^b Brankica Anđelić (2021). Direct mass measurements of No, Lr and Rf isotopes with SHIPTRAP and developments for chemical isobaric separation (PhD thesis). University of Groningen. doi:10.33612/diss.173546003.
^ Chatillon, A.; Theisen, Ch.; Greenlees, P. T.; Auger, G.; Bastin, J. E.; Bouchez, E.; Bouriquet, B.; Casandjian, J. M.; Cee, R.; Clément, E.; Dayras, R.; de France, G.; de Toureil, R.; Eeckhaudt, S.; Görgen, A.; Grahn, T.; Grévy, S.; Hauschild, K.; Herzberg, R. -D.; Ikin, P. J. C.; Jones, G. D.; Jones, P.; Julin, R.; Juutinen, S.; Kettunen, H.; Korichi, A.; Korten, W.; Le Coz, Y.; Leino, M.; Lopez-Martens, A.; Lukyanov, S. M.; Penionzhkevich, Yu. E.; Perkowski, J.; Pritchard, A.; Rahkila, P.; Rejmund, M.; Saren, J.; Scholey, C.; Siem, S.; Saint-Laurent, M. G.; Simenel, C.; Sobolev, Yu. G.; Stodel, Ch.; Uusitalo, J.; Villari, A.; Bender, M.; Bonche, P.; Heenen, P. -H. (1 November 2006). "Spectroscopy and single-particle structure of the odd- Z heavy elements 255Lr, 251Md and 247Es". The European Physical Journal A - Hadrons and Nuclei. 30 (2): 397–411. Bibcode:2006EPJA...30..397C. doi:10.1140/epja/i2006-10134-5. ISSN 1434-601X. S2CID 123346991. Retrieved 3 July 2023.
^ Heßberger, F. P.; Antalic, S.; Mistry, A. K.; Ackermann, D.; Andel, B.; Block, M.; Kalaninova, Z.; Kindler, B.; Kojouharov, I.; Laatiaoui, M.; Lommel, B.; Piot, J.; Vostinar, M. (20 July 2016). "Alpha- and EC-decay measurements of 257Rf". The European Physical Journal A. 52 (7): 192. Bibcode:2016EPJA...52..192H. doi:10.1140/epja/i2016-16192-0. ISSN 1434-601X. S2CID 254108438. Retrieved 3 July 2023.
^ Haba, H.; Huang, M.; Kaji, D.; Kanaya, J.; Kudou, Y.; Morimoto, K.; Morita, K.; Murakami, M.; Ozeki, K.; Sakai, R.; Sumita, T.; Wakabayashi, Y.; Yoneda, A.; Kasamatsu, Y.; Kikutani, Y.; Komori, Y.; Nakamura, K.; Shinohara, A.; Kikunaga, H.; Kudo, H.; Nishio, K.; Toyoshima, A.; Tsukada, K. (28 February 2014). "Production of 262Db in the 248Cm(19F,5n)262Db reaction and decay properties of 262Db and 258Lr". Physical Review C. 89 (2): 024618. doi:10.1103/PhysRevC.89.024618. Retrieved 2 July 2023.
^ ^a ^b Hulet, E. K. (22 October 1990). New, heavy transuranium isotopes. Robert A. Welch Foundation conference on chemical research: fifty years with transuranium elements. Lawrence Livermore National Lab., CA (USA). OSTI 6028419. Retrieved 3 July 2023.

Isotope masses from:
- M. Wang; G. Audi; A. H. Wapstra; F. G. Kondev; M. MacCormick; X. Xu; et al. (2012). "The AME2012 atomic mass evaluation (II). Tables, graphs and references" (PDF). Chinese Physics C. 36 (12): 1603–2014. Bibcode:2012ChPhC..36....3M. doi:10.1088/1674-1137/36/12/003. S2CID 250839471.
- 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
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.

[3] Lr – Excited nuclear isomer.

[4] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-5] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[6] Modes of decay:

SF: Spontaneous fission

[7] ( ) spin value – Indicates spin with weak assignment arguments.

[TNN-8] # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[11] The experiment in which alpha decay of two ²⁵¹Lr states was reported did not take into account spontaneous fission branches.^[3]

[12] Not directly synthesized, occurs as a decay product of ²⁵⁶Db

[20] Not directly synthesized, occurs as a decay product of ²⁸⁸Mc

[21] Not directly synthesized, occurs as a decay product of ²⁹⁴Ts

[NUBASE2020-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[Mc2022-2] Oganessian, Yu. Ts.; Utyonkov, V. K.; Kovrizhnykh, N. D.; et al. (2022). "New isotope ²⁸⁶Mc produced in the ²⁴³Am+⁴⁸Ca reaction". Physical Review C. 106 (064306). doi:10.1103/PhysRevC.106.064306.

[251Lr-9] Huang, T.; Seweryniak, D.; Back, B. B.; et al. (2022). "Discovery of the new isotope ²⁵¹Lr: Impact of the hexacontetrapole deformation on single-proton orbital energies near the Z = 100 deformed shell gap". Physical Review C. 106 (L061301). doi:10.1103/PhysRevC.106.L061301. S2CID 254300224.

[255Db-10] Leppänen, A.-P. (2005). Alpha-decay and decay-tagging studies of heavy elements using the RITU separator (PDF) (Thesis). University of Jyväskylä. pp. 83–100. ISBN 978-951-39-3162-9. ISSN 0075-465X.

[13] Vostinar, M.; Heßberger, F. P.; Ackermann, D.; Andel, B.; Antalic, S.; Block, M.; Droese, Ch.; Even, J.; Heinz, S.; Kalaninova, Z.; Kojouharov, I.; Laatiaoui, M.; Mistry, A. K.; Piot, J.; Savajols, H. (14 February 2019). "Alpha-gamma decay studies of 258Db and its (grand)daughter nuclei 254Lr and 250Md". The European Physical Journal A. 55 (2): 17. Bibcode:2019EPJA...55...17V. doi:10.1140/epja/i2019-12701-y. ISSN 1434-601X. S2CID 254115080. Retrieved 3 July 2023.

[14] Meng Wang; et al. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references". Chinese Physics C. 45 (3): 030003. Bibcode:2021ChPhC..45c0003W. doi:10.1088/1674-1137/abddaf. S2CID 235282522.

[thesis-15] Brankica Anđelić (2021). Direct mass measurements of No, Lr and Rf isotopes with SHIPTRAP and developments for chemical isobaric separation (PhD thesis). University of Groningen. doi:10.33612/diss.173546003.

[16] Chatillon, A.; Theisen, Ch.; Greenlees, P. T.; Auger, G.; Bastin, J. E.; Bouchez, E.; Bouriquet, B.; Casandjian, J. M.; Cee, R.; Clément, E.; Dayras, R.; de France, G.; de Toureil, R.; Eeckhaudt, S.; Görgen, A.; Grahn, T.; Grévy, S.; Hauschild, K.; Herzberg, R. -D.; Ikin, P. J. C.; Jones, G. D.; Jones, P.; Julin, R.; Juutinen, S.; Kettunen, H.; Korichi, A.; Korten, W.; Le Coz, Y.; Leino, M.; Lopez-Martens, A.; Lukyanov, S. M.; Penionzhkevich, Yu. E.; Perkowski, J.; Pritchard, A.; Rahkila, P.; Rejmund, M.; Saren, J.; Scholey, C.; Siem, S.; Saint-Laurent, M. G.; Simenel, C.; Sobolev, Yu. G.; Stodel, Ch.; Uusitalo, J.; Villari, A.; Bender, M.; Bonche, P.; Heenen, P. -H. (1 November 2006). "Spectroscopy and single-particle structure of the odd- Z heavy elements 255Lr, 251Md and 247Es". The European Physical Journal A - Hadrons and Nuclei. 30 (2): 397–411. Bibcode:2006EPJA...30..397C. doi:10.1140/epja/i2006-10134-5. ISSN 1434-601X. S2CID 123346991. Retrieved 3 July 2023.

[17] Heßberger, F. P.; Antalic, S.; Mistry, A. K.; Ackermann, D.; Andel, B.; Block, M.; Kalaninova, Z.; Kindler, B.; Kojouharov, I.; Laatiaoui, M.; Lommel, B.; Piot, J.; Vostinar, M. (20 July 2016). "Alpha- and EC-decay measurements of 257Rf". The European Physical Journal A. 52 (7): 192. Bibcode:2016EPJA...52..192H. doi:10.1140/epja/i2016-16192-0. ISSN 1434-601X. S2CID 254108438. Retrieved 3 July 2023.

[18] Haba, H.; Huang, M.; Kaji, D.; Kanaya, J.; Kudou, Y.; Morimoto, K.; Morita, K.; Murakami, M.; Ozeki, K.; Sakai, R.; Sumita, T.; Wakabayashi, Y.; Yoneda, A.; Kasamatsu, Y.; Kikutani, Y.; Komori, Y.; Nakamura, K.; Shinohara, A.; Kikunaga, H.; Kudo, H.; Nishio, K.; Toyoshima, A.; Tsukada, K. (28 February 2014). "Production of 262Db in the 248Cm(19F,5n)262Db reaction and decay properties of 262Db and 258Lr". Physical Review C. 89 (2): 024618. doi:10.1103/PhysRevC.89.024618. Retrieved 2 July 2023.

[261-262-19] Hulet, E. K. (22 October 1990). New, heavy transuranium isotopes. Robert A. Welch Foundation conference on chemical research: fifty years with transuranium elements. Lawrence Livermore National Lab., CA (USA). OSTI 6028419. Retrieved 3 July 2023.

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