Information on SIMS bargraphs

The SIMS bargraphs in this work were done at low mass resolution but were energy filtered to eliminate most molecular interferents. They were intended to provide an overview of mass species present on the feature. Since they were run immediately after the depth profile run was finished they might actually provide hints on species that were present at the beginning of the imaging process but were sputtered away before their mass was analyzed. Please have a look at the procedure sheet as well, if you want to familiarize yourself with this analysis.

An example bargraph is shown below. The underlying data may be obtained by clicking on the plot. You may then save the data as a text file from the applicable menu of your viewer application.

The data format is CSV, comma seperated values, which can be imported by most spreadsheets and plot software and is also the standard data format of BASIC text data files on most platforms. The datafile from the bargraph shown above looks like that:

"Title","Sensor 1252 C10"
"Date","04-07-1992"
"Primary Current",49.796001,"nanoamps"
"Primary High Voltage",41.000000,""
"Raster Size",250.000000,"microns"
"Imaged Field",60.000000,"microns"
"Energy Slit Opening",10.000000
"Energy Slit Translation",2.500000
"Entrance Slit Opening",1.088000
"Exit Slit Opening",10.000000
"Contrast Diaphragm",3.000000
"Field Aperture",2.000000
"Raster Size Pot. Setting",10.000000
0, 0
1, 68
2, 4
3, 1
4, 1
5, 1
6, 1
7, 2
...

Lines 14 and below contain the mass number the spectrometer was tuned to in column 1, and the number of counts (the signal intensity) for that particular mass in column 2. The intensity numbers are not corrected for ion yield efficiency as the mass spectrometer was operated in low resolution mode which makes species classification tentative.

Klaus G. Paul, 06-Jun-1994