Exact Masses of the Elements.
As part of a project for the Standards and Measurements Committee
of the American Society for Mass Spectrometry, the following
Tables have been assembled from literature data. It was reported
that the computer programs supplied by various manufacturers of mass
spectrometers were giving slightly different exact masses for a
given chemical formula. This was traced by Dr. Martha Vestling to
a problem with using different tables of atomic masses with the
correct algorithm. The following Tables appear to be the best data
available, and are accurate to far more than the needed number of
decimal places for almost all mass spectromteric needs.
Mass data are from
"The 1995 Update to the Atomic Mass Evaluation"
G. Audi and A.H. Wapstra, _Nuclear Physics_ A595 (1995) 409-480.
The data here were obtained from:
http://www.nea.fr/html/dbdata/mass_rmd_mas95.txt
and are the "recommended" values.
For more information, see:
http://iaeand.iaea.or.at/ndspub/masses/README.MAS95
Isotopic Abundances are from:
P. De Bievre and P.D.P. Taylor,
Int. J. Mass Spectrom. Ion Phys. *123* 149 (1993).
Lifetimes from: CRC
The data are in two tables:
Table of exact masses for all known isotopes, elements 1-111.
Table of only those isotopes with appreciable natural abundances or
halflives. This contains the "best" natural abundances
and halflives for the longer-lived radioactive isotopes.
This web page is maintained by:
John Bartmess, Dept. of Chemistry,
University of Tennessee, Knoxville TN 37996-1600.
bartmess@utk.edu