NAME

       Xray::Absorption::Chantler - Perl interface to the Chantler tables

SYNOPSIS

          use Xray::Absorption;
          Xray::Absorption -> load("chantler");

       See the documentation for Xray::Absorption for details.

DESCRIPTION

       This module is inherited by the Xray::Absorption module and provides access to the data contained in the
       Chantler tables of anomalous scattering factors and line and edge energies.

       The data in this module, referred to as "The Chantler Tables", was published as

         C. T. Chantler
         Theoretical Form Factor, Attenuation, and Scattering Tabulation
            for Z = 1 - 92 from E = 1 - 10 eV to E = 0.4 - 1.0 MeV
         J. Phys. Chem. Ref. Data 24, 71 (1995)

       This can be found on the web at

         http://physics.nist.gov/PhysRefData/FFast/Text/cover.html

       The Chantler data is available on the web at

         http://physics.nist.gov/PhysRefData/FFast/html/form.html

       More information can be found on the personal web page of C.T. Chantler

         http://optics.ph.unimelb.edu.au/~chantler/home.html

       The data contained in a database file called chantler.db which is generated at install time from the flat
       text files of the Chantler data.  The data is stored in a Storable archive using "network" ordering.
       This allows speedy disk and memory access along with network and platform portability.

       The required "File::Spec", "Chemistry::Elements", and "Storable" modules are available from CPAN.

METHODS

       The behaviour of the methods in this module is a bit different from other modules used by
       "Xray::Absorption".  This section describes methods which behave differently for this data resource.

       "get_energy"
           Example:

              $energy = Xray::Absorption -> get_energy($elem, $edge);

           This  behaves  similarly  to the "get_energy" method of the other resources.  When using the Chantler
           data resource, $edge can be any of K, L1-L3, M1-M5, N1-N7, O1-O5, or P1-P3.  Line  energies  are  not
           supplied with the Chantler data set.  The line energies from the McMaster tables are used.

       "cross_section"
           Example:

              $xsec = Xray::Absorption -> cross_section($elem, $energy, $mode);

           This  behaves  slightly differently from the similar method for the McMaster and Elam resources.  The
           Chantler tables contain anomalous scattering factors and the sum  of  the   coherent  and  incoherent
           scattering cross-sections.  The photo-electric cross-section is calculated from the imaginary part of
           the anomalous scattering by the formula

                mu = 2 * r_e * lambda * conv * f_2

           where,  "r_e"  is the classical electron radius, lamdba is the photon wavelength, and conv is a units
           conversion factor.

                r_e    = 2.817938 x 10^-15 m
                lambda = 2 pi hbar c / energy
                hbar*c = 1973.27053324 eV*Angstrom
                conv   = Avagadro / atomic weight
                       = 6.022045e7 / weight in cgs

           The $mode argument is different here than for the other resources.  The  options  are  "xsec",  "f1",
           "f2",  "photo", and "scatter" telling this method to return the full cross-section cross-section, the
           real or imaginary anomalous scattering factor, just the photoelectric  crosss-section,  or  just  the
           coherent and incoherent scattering, respectively.

           The  values  for  f1 and f2 are computed by linear interpolation of a semi-log scale, as described in
           the literature reference.  Care is taken to avoid the discontinuities at the edges.

EDGE AND LINE ENERGIES

       The Chantler data resource provides a fairly complete set of edge energies.  Any edge  tabulated  on  the
       Gwyn  William's Table of Electron Binding Energies for the Elements (that's the one published by NSLS and
       on the door of just about every hutch at NSLS) is in the Chantler data resource.  The Chantler data comes
       with the same, limited set of fluorescence energies as McMaster.

BUGS AND THINGS TO DO

       •   It would be nice to improve the inter-/extrapolation near absorption  edges.   As  it  stands,  these
           tables produce really poor DAFS output.

AUTHOR

         Bruce Ravel, bruce@phys.washington.edu
         http://feff.phys.washington.edu/~ravel/software/Absorption

perl v5.34.0                                       2022-06-28                    Xray::Absorption::Chantler(3pm)