
233Chronometry
TABLE 6.2 (Continued)
4n
+ 3 C
hronometers
235
U Chronometers, to be used with ingrown analytes
in
Usamples
E
lapsed Da
ys
231
Pa/
235
U
227
Ac/
235
U
3 4.5386E–12 2.9928E–19
10 2.2835E–11 5.7726E–18
20 4.9793E–11 2.6769E–17
40 1.0372E–10 1.1547E–16
70 1.8461E–10 3.6511E–16
100 2.6550E–10 7.5432E–16
130 3.4640E–10 1.2827E–15
170 4.5425E–10 2.2032E–15
220 5.8907E–10 3.6996E–15
300 8.0478E–10 6.8890E–15
400 1.0744E–09 1.2243E–14
550 1.4789E–09 2.3095E–14
700 1.8833E–09 3.7294E–14
850 2.2878E–09 5.4795E–14
1,000 2.6922E–09 7.5556E–14
1,300 3.5010E–09 1.2669E–13
1,700 4.5795E–09 2.1431E–13
2,200 5.9276E–09 3.5402E–13
3,000 8.0844E–09 6.4397E–13
4,000 1.0780E–08 ...