Fermium Isotopic Data

 

 

 

Isotope

 

Isotopic Mass

amu

 

% Abundance

 

T1/2

 

T1/2

Units

 

Mass Excess

KeV

 

Binding Energy

Per Nucleon

KeV

 

Decay

Mode

 

Branching

Ratio

242Fm

242.07343 (43)

 

800

us

68,400 (400)

7,465 (2)

SF

?

243Fm

243.07435 (23)

 

210

ms

69,260 (220)

7,464 (1)

A

60 40

244Fm

244.07408 (30)

 

3.3

ms

69,010 (280)

7,468 (1)

SF~100

 

245Fm

245.07539 (30)

 

4.2

s

70,220 (280)

7,465 (1)

A

?

246Fm

246.075299 (42)

 

1.1

s

70,141 (39)

7,468.2 (1.6)

A

?

247Fm

247.07685 (15)

 

35

s

71,580 (140)

7,465 (1)

A GE 50

 

248Fm

248.077195 (13)

 

36

s

71,906 (12)

7,465.91 (4.7)

A

93 7

249Fm

249.07903 (11)

 

2.6

m

73,620 (100)

7,461 (0)

B+ ?

 

250Fm

250.079521 (13)

 

30

m

74,074 (12)

7,462.08 (4.8)

A>90

 

251Fm

251.0815750 (90)

 

5.3

h

75,986.6 (8.4)

7,456.89 (3.3)

B+

98.20 13

252Fm

252.0824669 (61)

 

25.39

h

76,817.4 (5.7)

7,456.03 (2.3)

A~100

 

253Fm

253.0851852 (40)

 

3

d

79,349.5 (3.7)

7,448.46 (1.5)

EC

88 1

254Fm

254.0868542 (30)

 

3.24

h

80,904.2 (2.8)

7,444.79 (1.1)

A~100

 

255Fm

255.0899622 (52)

 

20.07

h

83,799.3 (4.8)

7,435.89 (1.9)

A

100

256Fm

256.0917731 (77)

 

157.6

m

85,486.1 (7.2)

7,431.78 (2.8)

SF

91.9 3

257Fm

257.0951047 (68)

 

100.5

d

88,589.5 (6.3)

7,422.20 (2.5)

A~100

 

258Fm

258.09708 (22)

 

370

us

90,430 (200)

7,418 (1)

SF~100

 

259Fm

259.10060 (30)

 

1.5

s

93,700 (280)

7,407 (1)

SF

100

260Fm

260.10268 (54)

 

1

m

95,640 (500)

7,403 (2)

SF ?

 

247mFm

247.07685 (15)

 

9.2

s

71,580 (140)

7,465 (1)

A~100

250mFm

250.079521 (13)

 

1.8

s

74,074 (12)

7,462.08 (4.8)

IT>80

 

251mFm

251.0815750 (90)

 

15.2

us

75,986.6 (8.4)

7,456.89 (3.3)

IT

100

247m1Fm

247.07685 (15)

 

 

 

71,580 (140)

7,465 (1)

0

 

255mFm

255.0899622 (52)

 

 

 

83,799.3 (4.8)

7,435.89 (1.9)

0

 

247m2Fm

247.07685 (15)

 

 

 

71,580 (140)

7,465 (1)

0

 

Data Source: ENSDF March 2005

©Radiochemistry Society 2005