Spectrum Acquisition

Select EDS Spectra from the Mode menu to display the EDS Spectra Toolbar, which controls spectrum acquisition, manipulation, and catalog management. Although they look slightly different due to operating system differences (above: Windows; below: Macintosh), they have the same controls:

Brief descriptions of each control on the toolbar are shown below:

Display markers for K, L, and M lines of selected elements

Superimpose selected regions of interest on the spectrum

Perform automatic peak identification

Perform Quant analysis and generate report

Beam energy

Beam current

Acquisition time for each spectrum

Clear current spectrum

Start spectrum acquisition

Zoom in

Zoom out

Pan

Select

Annotate Text

EDX Statistics for deadtime in %, input count-rate (Fast Channel), and output count-rate

• Acquiring an EDX Spectrum
• Calibrating the EDX Spectrum
• EDX Peak Identification
• EDX Quant Setup
• Quantitative Analysis
• Making a Standard
• Spectrum Overlays
• Import/Export of Spectra Files

Before acquisition, select the correct pulse processor in Hardware Setup (in toolbar mode, select Preferences from the Edit menu):

Select Hardware Setup from the prefs list and choose the correct pulse processor from the Processor menu in the Pulse Processor Settings:

While not strictly necessary at this point, the X-ray Probe prefs can be inspected and adjusted if desired:

With these simple preliminary steps completed, proceed to any of the following topics:

Creating a Catalog

Acquiring EDS Spectra

Setting ROIs and KLM Markers

Creating a Catalog

Select New Catalog from the File menu of the toolbar to create a new blank catalog window:

The catalog is simply a collection of spectra. To create new spectra within a catalog, select New from the File menu of the toolbar. Each new spectrum will be added to the catalog and can be selected with the spectrum menu:

When the catalog is created, the appropriate tools on the toolbar become available. The klm and roi buttons are always available. The PeakID and Quant buttons are available depending on the purchased feature set:

Acquiring EDS Spectra

Note: A catalog must be open in order to acquire a spectrum.

To acquire a spectrum into a catalog, simply click on the Acquire Spectra button in the toolbar:

The spectrum will be captured into the catalog and added to the spectrum menu. As many new spectra as desired can be created by selecting New in the File menu of the toolbar (second spectrum shown here):

Note that the Spectral Engine has one PHA input channel, so one spectrum can be acquired at a time.

Each spectrum display can be manipulated independently with the zoom-in, zoom-out, and slider tools in the toolbar, and the scaling tools in the catalog window:

zoom in (toolbar)

zoom out (toolbar)

slider (toolbar)

scaling (catalog window)

To zoom in, click on the magnifying glass (+) tool button and click inside the spectrum window. Each click in the spectrum window will zoom in on the area of the spectrum centered on the eV position of the magnifying glass. To zoom out, click on the magnifying glass (-) tool button and click inside the spectrum window. Each click in the spectrum window will zoom out from the area of the spectrum centered on the eV position of the magnifying glass. Hold down Alt or Option to swap (+) & (-).

To drag the spectrum to the left or right, click on the slider (hand) tool and drag inside the spectrum window. While holding the mouse button down, drag the spectrum left or right. To adjust the vertical scale (number of counts), use the Scale Menu above the spectrum. A pop-down menu will appear (default setting is Autoscale). A specific full-scale fixed value can be selected from the list, as can logarithmic scaling (default scaling is linear). Auto 80% autoscales the peaks to 80% of the maximum displayable height. To adjust the counts axis in steps without using the scale menu, use the green up and down arrow buttons in the Spectrum window.

The acquisition will accrue x-ray counts until the amount of time specified in the Dwell field of the toolbar. The Erase Spectra button (clr) will clear all counts out of a spectrum without stopping acquisition; this is a convenient way to observe a rapidly shifting spectrum during calibration or when deciding which area of the sample to probe.

When the toolbar first appears on screen, it displays in the upper right corner the Input Count Rate (Input) in counts/sec, the Output Count Rate (Output) in counts/sec, and the deadtime (Dead) percentage, all as reported by the pulse processor. Please review Tech Support Note 2000-1 regarding the measurement and interpretation of these values, in particular the deadtime value.

The Realtime and Livetime counters are updated in the upper left corner of the catalog window and measure seconds. Realtime is the total running clock time. Livetime is the total amount of time during which the pulse processor has not rejected pulses due to pileup. Please review Tech Support Note 2000-1 for more detailed information, including how the deadtime is calculated.

If the pulse processor and detector are properly installed and connected to the 4pi system, a spectrum appears immediately, although is it quite likely that the element peaks initially appear at the wrong energies because the system is not yet calibrated. To perform the calibration, 4pi strongly suggests starting with a sample whose spectrum will be easily recognized and can be used to calibrate the pulse processor (for example, Aluminum and Copper).

Setting KLM Markers and Manually-defined ROIs

KLM markers and manually-defined Regions of Interest (ROIs) can be overlaid independently on any spectrum in a catalog using the klm and roi buttons in the toolbar:

A KLM marker overlay:

A manual ROI overlay:

KLM and manual ROI overlays can be used in combination in any single spectrum. To select which individual KLM markers or manual ROIs appear in an overlay, right-click (control-click if using a one-button Macintosh mouse) in the toolbar on the klm (result shown below left) or roi button (result shown below right). KLM and ROI setup options are also avaliable with a control-click on the spectrum itself.

To turn on an element's KLM marker, single click its button to highlight (above left). The KLM marker for that element will immediately appear on the spectrum. To turn off an element's KLM marker, single click again to unhighlight. An identical procedure works to turn on or off a manual ROI overlay in a spectrum (above right). Unique to the KLM window, the keyboard arrow keys move the red selection box within the periodic table, and the KLM markers on the spectrum move accordingly. The spacebar toggles "sticky" activation of an element's markers.

To edit the individual manual ROI settings, Alt-click (Windows) or option-click (Macintosh) any element button in the X-ray Probe ROIs window (Copper shown here):		The Image Title is the name associated with the manual ROI.
		The Include checkboxes determine whether the manual ROI definition consists of K, L, or M lines (if applicable). The energy limits of each manual ROI (min/max) can be edited to suit the user (hence the term "manual"). Default values are supplied for most elements. See the discussion of the Auto ROI function for an important caveat.
		The Set Color button accesses the operating system's color-picking services, and allows you to select the manual ROI color. This color is applied to ROI overlays in any x-ray spectrum, and also to the ROI image in any x-ray map.

Direct Observation of Spectrum Data

A data flag can be overlaid independently on any spectrum in a catalog using the arrow button in the toolbar:

With the arrow button selected, double-click anywhere in the spectrum to make the flag appear:

The flag can be moved anywhere in the spectrum by dragging anywhere on the vertical black marker, to display the channel number, the number of counts in that channel, and the energy:

The flag can be precisely positioned to inspect the data for any channel (magnified, Cu KLM marker shown, flag is one channel away from the actual line at 8.04 KeV):

If the relevant ROI is also turned on (above, this page), the flag appends the total count summed over the whole ROI:

If background subtraction is also turned on, the flag appends the background-subtracted count summed over the whole ROI:

Operating note: to remove the flag, drag it off the spectrum to the right or left.