microCMA Length, the Long and Short of It

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RBD Instruments’ microCMA compact Auger electron energy analyzer is designed to fit on a standard 2.75″ / 70 mm CF flange. This makes it possible to add surface sensitive AES (Auger Electron Spectroscopy) to an existing vacuum chamber, as long as there is an available port.

The standard length of the microCMA analyzer is 11.1″ / 283 mm which works well for most 8″ / 200 mm diameter vacuum chambers. This standard length factors in a Z translator that is used to move the microCMA to the sample for analysis and to retract the microCMA when it is not in use. 

However, what if your flange-to-chamber distance is much longer or much shorter than the standard length? There is a 4.5″ / 114 mm limit on how short the microCMA can be due to the geometry of the analyzer section. For longer flange-to-target distances, the analyzer section can be extended as needed. The photo below shows a short 5″ microCMA and a long 21″ / 533.4 mm microCMA.

microCMA Auger Electron Spectrometer

No matter what your flange-to-target distance is, if you have a 2.75″ / 70 mm flange available, it is possible to add the surface-sensitive analytical AES technique to your chamber. The microCMA and Auger Electron Spectroscopy are especially useful for MBE chambers and other research experiments that deposit thin films and where surface-sensitive elemental analysis is required.

For more information on the microCMA visit RBD Instruments’ website here – microCMA

Putting Together a Compact UHV (Ultra-high Vacuum) Chamber for Spectroscopy

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Small, inexpensive UHV chambers have been the backbone of many commercial labs and universities for decades. The cost of larger, feature-rich systems has gone up dramatically in recent years, making compact, DIY chambers even more cost-effective for specialized applications and education.

RBD has a range of products available to add value to your compact chamber, and in fact built our own recently to develop and test our microCMA compact Auger analyzer.

RBD Kimball Chamber
Kimball Physics chamber with RBD miniZ, IG2, and microCMA compact Auger analyzer

The Chamber

We started with an 8 inch spherical octagon chamber from Kimball Physics. This chamber has two 8.00″ CF and eight 2.75″ CF mounts, with an internal volume of  106.6 cu. in. (1,747 cc):

Kimball Physics Chamber
Kimball Physics 8.0″ Spherical Octagon – Vacuum Chamber

The vacuum chamber was fitted with an ion pump from Gamma Vacuum, and valves and windows from MDC. Affordable turbo pumps can be sourced from Pfeiffer (HiCube 80 Eco) and Edwards (nEXT85).

Rough vacuum gauges are available from a number of companies including Digivac.

Rough Vacuum Gauge
Rough vacuum gauge

Ion gauges and ion gauge controllers are available from a number of companies including Stanford Research Systems

Ion Gauge Controller
Ion gauge controller

Accessories

To assist with water vapor desorption, the chamber is fitted with RBD’s miniZ. The mini-Z uses UVC radiation to desorb water from the chamber walls, resulting in faster pump-down times and lower ultimate vacuum.

RBD miniZ
RBD miniZ water vapor desorption system

This chamber is also fitted with RBD’s IG2 2 kV low cost sputter ion gun for specimen cleaning:

Instrumentation

The ultimate purpose of this system was to house RBD’s microCMA compact Auger analyzer (shown below with the Z translator attached):

RBD microCMA
RBD’s microCMA compact Auger Analyzer

For applications that require elemental analysis, this chamber, with the addition of a PC and CMapp AES acquisition and data massage software, is now a complete system providing quantitative, surface-sensitive Auger electron spectroscopy. At around $50,000 for all the components listed here, this is one example of a budget-sensitive spectroscopy system that can be assembled, repaired and upgraded without costly field service visits.

microCMA Software Update – New Features for Auger Multiplexes

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This past year there have been a number of new features added to CMapp – the application software for the microCMA. Most of these provide you with improved (and safer) control of your microCMA hardware. For example, there’s is now a “Dynamic Mode” feature that assists in automatically conditioning the multiplier.

The most significant addition to the CMapp software is the Multiplex Survey Region View.

Earlier versions of CMapp – like its AugerScan cousin – displayed Multiplex data in two ways – either individual survey region windows, or a bar graph representing the peak-to-peak or atomic concentration (a.c.) data.

The most recent version of CMapp (0.4) has an additional view, which displays the survey region data in one graph of kinetic energy vs. counts or concentration. It’s now much easier to visualize all of the survey data in one window. Additionally, the graph updates in real-time while acquiring, much like a single survey.

CMapp Mutiplex By Energy
Multiplex Region View (legend ordered by energy)

This latest feature was actually added to CMapp in a recent previous version, but we’ve updated it to provide the option to order data legend and atomic concentration table by energy, alphabetically, by descending atomic concentration, or by the order the regions were added to the acquisition.

CMapp Mutiplex By Energy
Multiplex Region View (legend ordered by atomic concentration)

You can change the order of regions in the legend (and in the optional atomic concentration annotation) in the View menu – choose the Options command, Graph tab:

CMapp View Options - Graph
CMapp View Options Dialog – Multiplex Legend Options

You can find more information about RBD’s microCMA and download the latest version of CMapp here.

We’ll be soon be updating our YouTube channel with more microCMA tutorial videos to help you get the most out of your compact Auger analyzer and CMapp software.