Element Library *

The "Element Library" dialog window provides the means of managing the information used to identify spectral features and then create regions and components with predefined values. The three property pages offer two views of the data held in the element library file, plus a means of loading/merging data into the current session.

Figure 1: Main Toolbar.

The element library file is an ASCII file. The first line is the version number. Each subsequent entry in the file has items that are included one per line as follows.

1.	Element
2.	Transition
3.	Label/Name
4.	Mass (Daltons)
5.	Energy Type (B.E. or K.E.)
6.	Energy (eV)
7.	F.W.H.M.
8.	Line shape (e.g. GL(30))
9.	Relative Sensitivity Factor
10.	Ionisation source (X ray anode)

Photoelectric transitions should be entered with item 5 (energy type) set to "BE"; this allows the same energy to be used for different X-ray anodes. Auger lines always appear at the same kinetic energy independent of the excitation source and these values should be specified with energy type "KE".

Note that the ionisation source is also specified so that source specific information can be offered for spectra that match the acquisition characteristics found in the library.

An entry allows the species and transition to be specified but also permits a name other that these two labels to be also entered. For example, a carbon line corresponds to a chemical state arising from PVC is identified by entering, "C" for the species, "1s" for the transition and "C 1s PVCa" for the name. It is the name that appears as the first item in the scrolled list of transitions.

Although the expected energies for X-ray induced transitions are universal constants, quantification data will be (in practice) specific to an instrument. An element library can be customised through the energy-ordered scrolled list on the property page labelled "Element Table". Right clicking on an item name will produce a dialog window that allows the items associated with the indicated line to be updated. New entries can be created using this mechanism but for large numbers of new entries a text editor with cut and paste can be the best method of modifying the element library.

The items that are specific to an instrument are the relative sensitivity factors (R.S.F.), full width half-maximum (F.W.H.M.) and the line shape. Instrument manufacturers will supply some of this information, but individual experience will determine values for items such as the F.W.H.M. and line shapes. These values are only to speed up the creation of synthetic components with values that are sometimes useful!

The property page labelled "Input" allows the session element library to be modified by reading different element library files. A browser button offers a file selection dialog and the chosen file may be loaded or merged with the current session element library. If the "Load" button is selected, the element library in the current session is replaced by the contents of the specified file. Alternatively, the "Merge" button causes the contents of the file to be added to the existing information for the session.

A user can maintain a set of element library files and load/merge only those appropriate for a type of sample or operating mode of the instrument. In the absence of transmission function data this mechanism allows the user to maintain different R.S.F. values for different acquisition conditions.

Peak identification is performed using the scrolled list of transitions and the "Periodic Table" property page. A spectrum may be viewed with markers at the energies where peaks might be expected (Figure 2). To add and remove these markers, select an element through either the periodic table interface or from the element table. The markers are toggled on and off by repeatedly selecting the same element.

An alternative method for examining a spectrum is to have the scrolled element table visible and then run the cursor over the tile display window with the left mouse button held down. The energy order list will scroll with the energy position of the cursor. Release the mouse button when over a peak of interest and then use the table to toggle the peak markers until a match is established.

The peak markers are maintained within a session on a spectrum by spectrum basis. Switching the marks on one spectrum does not change those previously chosen for some different data. Simply select the tile used to display the data and the periodic table will update to reflect the state of the markers chosen for that spectrum.