# Overview of Atomic and X-ray Data

The data provided in XrayDB includes Atomic data and characteristic energies and cross sections for the interaction of X-rays with elements. A few definitions and conventions necessary for using this data are discussed here.

## Elements

Most of the data resources are accessed by an elements Atomic Symbol. For the Python module, most methods will take element as the first argument, and this can either be the integer atomic number or the string for the atomic symbol.

## Physical Units

Elemental densities are given in gr/cm^3, and molar masses are given in AMU. Unless otherwise stated, all energies are in units of eV.

## X-ray Edges

Several resources (database tables, python methods) take either an `edge` or a `level` argument to signify a core electronic level. These are strings and must be one of the levels listed in the Table of X-ray edge names.

> Table of X-ray Edges and Core electronic levels. The Names are the IUPAC symbols for the core electronic levels.

> > Name | electronic level | Name | electronic level
> > --- | --- | --- | ---
> > K | \(1s\) | N5 | \(4d_{5/2}\)
> > L3 | \(2p_{3/2}\) | N4 | \(4d_{3/2}\)
> > L2 | \(2p_{1/2}\) | N3 | \(4p_{3/2}\)
> > L1 | \(2s\) | N2 | \(4p_{1/2}\)
> > M5 | \(3d_{5/2}\) | N1 | \(4s\)
> > M4 | \(3d_{3/2}\) | O3 | \(5p_{3/2}\)
> > M3 | \(3p_{3/2}\) | O2 | \(5p_{1/2}\)
> > M2 | \(3p_{1/2}\) | O1 | \(5s\)
> > M1 | \(3s\) | P3 | \(6p_{3/2}\)
> > N7 | \(4f_{7/2}\) | P2 | \(6p_{1/2}\)
> > N6 | \(4f_{5/2}\) | P1 | \(6s\)

## X-ray Lines

Many resources (database tables or methods) take emission line arguments. These are all strings and follow the latinized version of the Siegbahn notation as indicated in the Table of X-ray emission line names.

> > Table of X-ray emission line names and the corresponding Siegbahn and IUPAC notations

> Name | IUPAC | Siegbahn | Name | IUPAC | Siegbahn
> --- | --- | --- | --- | --- | ---
> Ka1 | K-L3 | \(K\alpha_1\) | Lb4 | L1-M2 | \(L\beta_4\)
> Ka2 | K-L2 | \(K\alpha_2\) | Lb5 | L3-O4,5 | \(L\beta_5\)
> Ka3 | K-L1 | \(K\alpha_3\) | Lb6 | L3-N1 | \(L\beta_6\)
> Kb1 | K-M3 | \(K\beta_1\) | Lg1 | L2-N4 | \(L\gamma_1\)
> Kb2 | K-N2,3 | \(K\beta_2\) | Lg2 | L1-N2 | \(L\gamma_2\)
> Kb3 | K-M2 | \(K\beta_3\) | Lg3 | L1-N3 | \(L\gamma_3\)
> Kb4 | K-N4,5 | \(K\beta_2\) | Lg6 | L2-O4 | \(L\gamma_6\)
> Kb5 | K-M4,5 | \(K\beta_3\) | Ll | L3-M1 | \(Ll\)
> La1 | L3-M5 | \(L\alpha_1\) | Ln | L2-M1 | \(L\nu\)
> La2 | L3-M4 | \(L\alpha_1\) | Ma | M5-N6,7 | \(M\alpha\)
> Lb1 | L2-M4 | \(L\beta_1\) | Mb | M4-N6 | \(M\beta\)
> Lb2,15 | L3-N4,5 | \(L\beta_2,L\beta_{15}\) | Mg | M3-N5 | \(M\gamma\)
> Lb3 | L1-M3 | \(L\beta_3\) | Mz | M4,5-N6,7 | \(M\zeta\)

## Cross Sections

The photo-absorption and scattering cross sections from [Elam, Ravel, and Sieber (2002)] and [Chantler (2000)] are in cm^2/gr.

The data from [Elam, Ravel, and Sieber (2002)] is held as logarithms of energy, cross section, and logarithm of the 2nd derivative of cross section that allows for cubic spline interpolation in log-log space.