ISIS - overview of x-ray procedures

Start Labbook and choose job

ISIS uses the Labbook application to manage data files and to launch applications. Each

registered user will have a job assigned to them according to their last use. Therefore, it is good

to have multiple users registered so that both user and job do not have to be changed at the

beginning of each session.

Start Labbook (if not already running) with the icon on the QuickLaunch toolbar or on the

desktop.

Choose user from the list and click OK.

Change Job, if necessary.

Start the “standard” programs. AutoColumn, AutoUpdate, and Tetra should be started as a matter

of course.

AutoColumn is used to display (and set) the SEM parameters. It is helpful to have this running to

ensure that the conditions which the ISIS system has read are indeed the same as the those to

which the SEM is set. There is a delay (sometimes considerable) in the update of values from the

SEM. It is best to ensure that the correct values are on record before collecting data, especially

images.

AutoUpdate is used to toggle polling of SEM conditions on and off. This will normally be set on

when Labbook is first started. However, it may be off if Labbook was already running. It is best

to run AutoUpdate to be certain. Polling should be turned off when taking multiple photographs.

It may also be turned off once the important conditions (kV and WD) have been read.

Magnification is important for images and especially for line scans, but it may be ignored for x-

ray spectra and maps.

Tetra is used to control the Tetra BSE detector. Since that detector is used for most composition

imaging, the control program should be started.



Click on the appropriate icon to start the desired task, usually X-ray analysis. Imaging and

Automation are also common tasks.



Set SEM conditions for the task. The following conditions are used for more than 95% of x-ray

work. Other conditions may be chosen or recommended in conjunction with lab staff. Because

these conditions are used frequently, they have been stored under parameter set #5 under Shift-

F10.

 25 mm working distance. (the detector is aimed at this height)

 X-ray detector in.

 20 kV (needed for good excitation of all x-ray lines)

 195 beam current (for good count rates)

 40 Pa atmosphere (needed only for insulating specimens)

 X-ray setup for Selectable, Light element mode, Process constant 4 (these are not the default

settings, but are normally setup for new users). For higher throughput, light element mode

may be turned off (i.e., select Fast Counting mode).



Check count rate using X-ray application.

 Locate an area of the sample with a good intensity. Ensure the raster is completely on the

area of interest and not overhanging the edge of the sample. Metals are usually more

intense than oxides which are more intense than inorganic materials or polymers

 Start acquiring a spectrum.

 Adjust beam current (F10) and or EDS detector position to 30-40% deadtime. Note: some

samples may not tolerate high currents without charging or thermal damage.

 Note: there is a tradeoff between signal quality and spatial resolution. BSE signal quality

benefits from high current. Current may be set high for a good quality image and the EDS

detector may be withdrawn to reduce the count rate. For highest count rate with the least

current, insert the EDS detector as far as it can go and reduce the beam current with F10

to a maximum of 40% deadtime. Even lower count rates may be used but will prolong the

counting time for the same precision in the results.

 Set the signal contrast and brightness for the beam current chosen.

Collecting X-ray maps



 Recall or paint x-ray windows. Many are already defined and may be used as a starting point.

 Consider a background window using an element not present, e.g., Argon.

 Edit names. Rename background window to “bkgd” and rename windows for overlapping

lines, e.g., P-Zr or Na-Zn. You may also shorten long window designations (e.g., Na Ka1 to

Na or NaKa).

 Start Speed-Map (icon on X-ray analysis program)

 Define acquisition setups

Number of frames. We normally find 40 frames to be quite adequate at moderate count

rates. More frames will improve the appearance of the maps. I discourage collecting less

then 20 frames.

Pick map size. Maps smaller than 256 pixels are suitable only for very gross structures.

Maps of 512 pixels are limited to only 6 elements along with the image.

256 pixel maps require about 15 seconds per frame scan. Thus, a 40-frame scan requires

about 10 minutes.

512 pixel maps require about 60 seconds per frame scan. Thus, a 50-frame scan requires

more than 45 minutes. However, fewer frames might give quite suitable detail in the

maps.

 Start the scan.

 Wait.

 Save the results.

 Recall the file. This brings up the sample ID and allows for faster processing. It also allows

for point analysis at areas of interest in the map.

 Size the window to fit the maps and “tidy” the display. Fine-tune the window size to just

encompass the maps of interest. Save the layout for future use.

 Adjust map brightness and contrast (Ctrl-E).

 Copy bitmap (Edit, Copy Results) and paste into PCI or similar program. Convert the image

to grayscale and save the file in GIF format for portability.

 Print the map set.

Collecting images

 Working distance for whatever is suitable for imaging.

 X-ray detector out for working distances of less than 25 mm.

 Beam voltage and current set for “good” image signal and resolution. Higher resolution

generally requires lower current while good quality requires more current and/or shorter

working distance.



 Start Speed-Map

 Define acquisition setups

 Pick map size. Maps smaller than 256 pixels are suitable only for very gross structures. Maps

of 512 pixels are limited to only 6 elements along with the image.

 256 pixel maps require about 15 seconds per frame scan. Thus, a 50-frame scan requires

about 12 minutes.

 512 pixel maps require about 60 seconds per frame scan. Thus, a 50-frame scan requires

more than 45 minutes. However, fewer frames might give quite suitable detail in the maps.

 Start the scan.

 Wait.

 Save the results.

 Recall the file if you want the label to appear.

 Size the window to fit the maps and “tidy” the display. Fine tune the window size to just

encompass the maps of interest. Save the layout for future use.

 Adjust map brightness and contrast.

 Save bitmap to a file for portable, digital format (File, Print, Save Results). Limit file name to

8 characters. The name may be lengthened later, and the file may be converted from DIB

(~BMP) format to GIF for portability.

Print the map s