Bruker M4 TORNADO User Manual

Using the M4 TORNADO Software
M4 TORNADO
115
6.9.6.2 Different methods for the determination of phases
The Histogram method basically operates within a virtual n-dimensional ‘element space’. The
intensity of every mapped element spans one axis of this space. The chemical composition of
each pixel in the map is virtually plotted as a single point into the space. That means pixels
containing the same or similar chemical composition are within the same region of this space –
they represent a particular phase. The more pixels/points plot close together, the higher is the
modal abundance of this phase within the map.
The Histogram method offers two options: PCA and Auto, which can also used combined. PCA
stands for Principal Component Analysis, which is a mathematical method for reducing the
dimensions of the data set. The result of this kind of vector analysis can be visualized as
histograms that contain the most relevant chemical information, whereas insignificant information
is disregarded. In order to separate the phases within a histogram, its x-axis needs to be
segmented. If only the box for PCA is checked, the segments have a constant distance, which
sometimes leads to the artificial separation of a single phase. Therefore, it is recommended to
also check the box for Auto, where the segments are set automatically, adjusting their size to
better separate the actual phases. In both cases, increasing the value on the Sensitivity slide bar
will lead to an increase of the number of phases.
The Cluster method basically works by a comparison of the chemical composition of one pixel to
the neighboring pixel within a map. The program runs through the map pixel by pixel and merges
pixels with similar composition into one phase, depending on the sensitivity chosen. The higher
the value is set on the Sensitivity slide bar, the more phases are identified.
With the Object method, a phase image can be produced based on the user’s knowledge of the
sample. Every phase that should appear within the phase image needs to be pre-selected under
the Map result tab using the pipette tool (see 6.9.3.2). If a HyperMap was acquired, it helps to
compare the spectra of the selected regions/objects within the map in order to decide which and
how many phases are present. The size and shape of the objects drawn into the map has little
influence on the AutoPhase result as long as a reasonable amount of pixels is selected. However,
if there are phases that occupy a very small area of the map, the Area slide bar should be set to
0.
The phase image is created (by clicking the AuthoPhase button) based on the chemical
composition of the pre-defined objects, as AutoPhase will group every pixel of the map into one
phase with the selected object that is closest in composition.
The selected objects are visible within the phase image, but can be deleted (by pressing the Del
key on the keyboard) before saving the image.
6.9.6.3 Additional tools for phase evaluation
Merging phases. Several phases can be merged into a single phase by highlighting (pressing
the shift key) the particular phases in the clipboard and pressing the merge icon.
Displaying and quantifying spectra of the phases. If a HyperMap database was used to
produce the phase image, a spectrum can be displayed for each phase by highlighting (pressing
the shift key) the phases of interest in the clipboard and pressing the button. The spectra
are then displayed within the Spectrum tab and can be quantified by selecting a quantification
method and using the Quantify button as described in section 6.4.3.3.

Bruker M4 TORNADO Specifications

General

Brand	Bruker
Model	M4 TORNADO
Category	Measuring Instruments
Language	English