
		Low-Energy X-ray Interaction Coefficients:
		Photoabsorption, Scattering, and Reflection
			E = 30-30,000 eV, Z = 1-92

	        B. L. Henke, E. M. Gullikson, and J. C. Davis
			Center for X-Ray Optics, 2-400
			Lawrence Berkeley Laboratory
			Berkeley, California 94720

These files were used to generate the tables published in reference [1].
The files contain three columns of data: Energy(eV), f_1, f_2,
where f_1 and f_2 are the atomic (forward) scattering factors.
There are 500+ points on a uniform logarithmic mesh with points
added 0.1 eV above and below "sharp" absorption edges.
(Note: below 29 eV f_1 is set equal to -9999.) 
The tabulated values of f_1 contain a relativistic, energy independent,
correction given by, Z* = Z - (Z/82.5)^(2.37).

The atomic photoabsorption cross section, mu_a, may be readily obtained
from the values of f_2 using the relation,

			mu_a = 2*r_0*lambda*f_2 

where r_0 is the classical electron radius, and lambda is the wavelength.
The index of refraction for a material with N atoms per unit volume
is calculated by,

		n = 1 - N*r_0*(lambda)^2*(f_1+if_2)/(2*pi).

These (semi-empirical) atomic scattering factors are based upon
photoabsorption measurements of elements in their elemental state.
The basic assumption is that condensed matter may be modeled as a
collection of non-interacting atoms.  This assumption is in general
a good one for energies sufficiently far from absorption thresholds.
In the threshold regions, the specific chemical state is important
and direct experimental measurements must be made.

These tables are based on a compilation of the available experimental
measurements and theoretical calculations.  For many elements there is
little or no published data and in such cases it was necessary to
rely on theoretical calculations and interpolations across Z.
In order to improve the accuracy in the future considerably more
experimental measurements are needed.

Please send any comments to EMGullikson@lbl.gov.

Note that the following elements have been updated since the publication
of Ref. [1] in July 1993.  Check 

    http://henke.lbl.gov/optical_constants/update.html 
    
for more recent updates.

========  ==========   =================
Element   Updated      Energy Range (eV)
========  ==========   =================
Pt        Aug 2023     0.1-800
Cr        Aug 2023     0.4-813
Nb        Aug 2023     10-1000
Y         Aug 2023     50-1300
Er        Aug 2023     3-1580
Mg        Jan 2011     10-1300
Zr        Apr 2010     20-1000
La        Jun 2007     14-440
Gd        Jun 2007     12-450
Sc        Apr 2006     50-1300
Ti        Aug 2004     20-150
Ru        Aug 2004     40-1300
W         Aug 2004     35-250
Mo        Aug 2004     25-60
Be        Aug 2004     40-250
Mo        Nov 1997     10-930
Fe        Oct 1995     600-800
Si        Jun 1995     30-500
Au        Jul 1994     2000-6500
Mg,Al,Si  Jan 1994     30-200
Li        Nov 1994     2000-30000
========  ==========   =================

[1]  B. L. Henke, E. M. Gullikson, and J. C. Davis,
Atomic Data and Nuclear Data Tables Vol. 54 No. 2 (July 1993).

