isotope ratios  search
RTAl-27/Al-26
 Ar-38/Ar-36
 Ar-40/Ar-36
 Ar-40/Ar-39
 Ar/Ar
 B-11/B-10
 Be-10/Be-9
 C-13/C-12
 C-14/C-12
 Cl-37/Cl-35
 Cr-53/Cr-52
 D/H
 He-4/He-3
 He/He
 Hf-177/Hf-176
 I/Xe
 Io/Th
 Io/U
 isotopes
 K/Ar
 Kr/Kr
 Lu/Hf
 Mg-25/Mg-24
 Mg-26/Mg-24
 N-15/N-14
 Nd-144/Nd-143
 Nd/Nd
 Ne-22/
SNA valid term through 1972. From 1972-1992, also search ratios AND isotopes. Also see isotopes, absolute age and name of chemical element. Added to Thesaurus in 1993.