Loading VGX900 (Ron Unwin)


Ron Unwin developed the VGX900 system and so all the various forms of Ron Unwin’s files can be converted in the same way.


Files generated by the VGX900 system are ACSII files and each file may contain one or more spectral regions. The method for loading these files into CasaXPS is to collect a set of the files in a sub-directory and then enter a new filename in the “Convert to VAMAS file” dialog window, but add an extension of .unw to the specified name (Figure 1). All files in the directory will be read and appear in a single VAMAS file. Since the files have no characteristic file type it is essential that only files generated from the VGX900 system are present in the sub-directory and no others.


Some formats of the VGX900 system do not include information necessary for a proper description of the data (in the VAMAS sense), but the system does allow the writing of VAMAS files based on a user specified template. This allows data to written in a form directly readable by CasaXPS, but the user must ensure that the correct fields have been used to describe the spectra.


Alternatively, the conversion option in CasaXPS can specify some of the missing information using flags. The X-ray anode defaults to Aluminium and the energy-scale defaults to Binding Energy. Appending the following strings to the file name at conversion time can alter these two options:

-anode Mg       specifies Magnesium anode

-energy KE      specifies that the scans were performed using an increasing KE sweep.



Figure 1: Convert to VAMAS file dialog window. Note the .unw extension used to indicate that the set of files contain spectra acquired using Ron Unwin's data system. The –anode Mg is only used to force the X-ray source to be Magnesium instead of the default setting. The latest release of Ron Unwin’s system includes this information.


Figure 2: The set of spectra contained in the sub-directory shown in Figure 1 are offered in CasaXPS using the browser and spectrum display frames.