Fermium: Properties


Isotopes
  Natural
Abun. (%)
Atomic
Mass
Half-
life
Decay Mode
/Energy (/MeV)
Part. En.
/Intensity
(MeV/%)
Cross-sect.
Ther. Neut.
(b)
Spin
(h/2 pi)
Magnetic
Dipl.Mom.
(nm)
Electric
Quad. Mom.
(b)
Gamma En.
/Intensity
(MeV/%)
 242Fm     0.8ms S.E.           
 243Fm   243.07446 0.2s alpha 8.55         
 244Fm   244.07412 3.7ms S.E.    0+      
 245Fm   245.07625 4s alpha 8.15         
 246Fm   246.07529 1.2s alpha,S.E. 8.24  0+      
 247mFm     9s alpha 8.18         
 247Fm   247.0768 35s alpha/ 8.2
E.C./ 3
7.87/ 70
7.93/ 30
        
 248Fm   248.077171 36s alpha/ 8.001
S.E.
7.83/ 20
7.87/ 80
 0+      
 249Fm   249.07891 3m E.C./ 2.4
alpha
 
7.53
 7/2+      
 250mFm     1.8s I.T.           
 250Fm   250.079509 30m alpha,E.C./ 0.8 7.43  0+      
 251Fm   251.08159 5.3h E.C./ 1.47
alpha
 
6.833
 9/2-      
 252Fm   252.082466 1.058d alpha/ 7.154
S.E.
6.998/ 15
7.039/ 85
 0+      
 253Fm   253.085173 3d E.C./ 0.33
alpha
6.676
6.943
 1/2+     Es k x rays
0.2719
 254Fm   254.086846 3.24h alpha,S.E. 7.15
7.192
 0+      
 255Fm   255.089948 20.1h alpha 6.9635/ 5
7.0225/ 93.4
26 b7/2+      
 256Fm   256.091767 2.63h S.E.,alpha 6.92  0+      
 257Fm   257.075099 100.5d alpha,S.E. 6.519  9/2+     0.1794
0.241
 258Fm     0.37ms S.E.           
 259Fm     1.5s S.E.