Analytical Conditions versus Column Conditions

EPMA Probe

Analytical Conditions versus Column Conditions

In the first method, (using specified values for kilovolts, beam current and beam size) the user directly specified the analytical conditions. In the second method, a specified string is used to indicate a column condition that is stored internally in the instrument. In this latter case, because the actual value of the operating voltage (kilovolts) in the column condition string is ambiguous, the user should be sure that the single value fields are also correctly specified based on the column condition string specified.

 

For example, the SX100/SXFive supports the use of externally stored column conditions. Therefore, if the column condition option is selected, and the column condition is specified as "15 keV, 20 nA, 5 um.PCC" (indicating a column condition at 15 keV), then the user should also be sure that the kilovolts field is correctly specified as 15 keV. Failure to properly specify the kilovolts field when using column condition strings will cause the ZAF or Phi-Rho-Z matrix corrections to be inaccurate. The beam current field is also used in some cases to check for beam drift.

 

For accurate documentation purposes it is also preferred that the beam current and beam size fields are also properly specified when using column condition strings. If, as in the above example, the "15 keV, 20 nA, 5 um.PCC" column condition file also includes a beam current of 20 nA and a beam size of 5 um, then those values should also be specified in the single values fields even though are not actually used in the acquisition procedure. This maintains the accuracy of the documented sample conditions.

Note that because samples at different operating voltages can be acquired in a single run, standards at the corresponding voltages must also be acquired for quantitative calculations.