## Experimental Edge Energies (Direct, Combined, and Vapor)

See also non-edge
experimental transition
energies.
Values for the absorption edge energies were obtained using two different
procedures: 1) direct x-ray absorption measurements which remove an
electron from the inner-shell of interest to infinity and
2) combinations of transition energies between inner and outer shells
and the electron binding energies of the outer shells.

The set of direct absorption measurements includes some entries obtained with
crystals of known lattice spacing [13,14,15] and
re-scaled absorption edge values from the Bearden database
[1] and other sources [16].
The numerical values for these directly measured edges are given in the
"Experimental Energy - Direct" column. Except for the rare gases
all of these entries are for solid targets. The numbers in the reference
column with the subscript "d" are for the direct absorption
measurements.

The combination procedure uses electron binding energies for the L, M, and
N shells found in references [82-87] and
inner shell transition energies available in this database. For most edges and
elements, there are several combinations of transitions and binding energies
(alternate routes) that produce values for the edge location. Numerical values
and uncertainties can be obtained as the average and 1 standard deviation
spread of these alternate routes, respectively, and are given in the
"Experimental Energy - Combined" column. The table does not
contain references for the edges obtained by the combination procedure.

There are a few edge measurements using the vapor phase of elements with
*Z* in the 20 to 29 and 62 to 70 ranges
[17-22]. Because these measurements closely
approximate free atoms and the theoretical calculations assume free atoms, we
include these measurements in the table. The numerical values for the vapor
measurements are in the "Experimental Energy - Vapor" column.
The numbers in the reference column with the subscript "v" are for
the vapor edge measurements.