Isotopes of dubnium
List of isotopes
Abbreviations: EC: Electron capture IT: Isomeric transition SF: Spontaneous fission Existence of this isomer is unconfirmed Heaviest nuclide known to undergo β⁺ decay Not directly synthesized, occurs in the decay chain of ²⁸²Nh Not directly synthesized, occurs in the decay chain of ²⁸⁷Mc Not directly synthesized, occurs in the decay chain of ²⁸⁸Mc Not directly synthesized, occurs in the decay chain of ²⁹⁴Ts

Isotopes of dubnium

Section Title: List of isotopes
Table Section Text: Abbreviations: EC: Electron capture IT: Isomeric transition SF: Spontaneous fission Existence of this isomer is unconfirmed Heaviest nuclide known to undergo β⁺ decay Not directly synthesized, occurs in the decay chain of ²⁸²Nh Not directly synthesized, occurs in the decay chain of ²⁸⁷Mc Not directly synthesized, occurs in the decay chain of ²⁸⁸Mc Not directly synthesized, occurs in the decay chain of ²⁹⁴Ts

nuclide symbol	Z(p)	N(n)	isotopic mass (u)	half-life	decay mode(s)	daughter isotope(s)	nuclear spin and parity

excitation energy

255Db	105	150	255.10707(45)#	1.7(5) s	α (~80%)	251Lr

SF (~20%)	(various)

256Db	105	151	256.10789(26)#	1.9(4) s [1.6(+5−3) s]	α (~64%)	252Lr

SF (~0.02%)	(various)

β+ (~36%)	256Rf

257Db	105	152	257.10758(22)#	1.53(17) s [1.50(+19−15) s]	α (>94%)	253Lr	(9/2+)

SF (<6%)	(various)

β+ (1%)	257Rf

257mDb	140(100)# keV	0.67(6) s	α (>87%)	253Lr	(1/2−)

SF (<13%)	(various)

β+ (1#%)	257Rf

258Db	105	153	258.10929(33)#	4.5(4) s	α (64%)	254Lr

β+ (36%)	258Rf

SF (<1%)	(various)

258mDb	60(100)# keV	1.9(5) s	β+	258Rf

IT (rare)	258Db

259Db	105	154	259.10949(6)	0.51(16) s	α	255Lr

260Db	105	155	260.1113(1)#	1.52(13) s	α (>90.4%)	256Lr

SF (<9.6%)	(various)

β+ (<2.5%)	260Rf

260mDb	200(150)# keV	19 s

261Db	105	156	261.11192(12)#	4.5(1.1) s	SF (73%)	(various)

α (27%)	257Lr

262Db	105	157	262.11407(15)#	35(5) s	SF (~67%)	(various)

α (~30%)	258Lr

β+ (3#%)	262Rf

263Db	105	158	263.11499(18)#	29(9) s [27(+10−7) s]	SF (~56%)	(various)

α (~37%)	259Lr

β+ (~6.9%)	263Rf

266Db	105	161	266.12103(30)#	80(70) min	SF	(various)

EC	266Rf

267Db	105	162	267.12247(44)#	4.6(3.7) h	SF	(various)

EC	267Rf

268Db	105	163	268.12567(57)#	30.8(5.0) h	SF (~100%)	(various)

EC	268Rf

270Db	105	165	270.13136(64)#	1.0 (+1.5−0.4) h	SF (17%)	(various)

α (83%)	266Lr

EC	270Rf

Sentence(s)

The longest-lived known isotope is ²⁶⁸Db.

final_sentence: The longest-lived known isotope is ²⁶⁸Db.