WP 4: analytical studies

The objective of work package 4 on analytical studies is the investigation of pulsed rf Glow Discharge analysis of non-conductive thin films. The examination of quantification methods of non-conducting materials and the quantification of light elements for nanostructured materials, polymers and impurities in silicon. Investigation of the analytical potential of a newly developed double focussing GD-MS instrumentation. Exploration of GD-ToFMS for the analysis of macromolecular materials, in particular of the effect of hard and soft ionisation processes on long molecular chains in the pulsed GD plasma. Quantification of hydrogen in steels. Study of factors affecting GD-MS results.
Most Gladnet member groups participate in the training and research activities of WP 4, most of the analytical work, however is performed in the following laboratories.


Green Cu-emission in a plasma plume

EMPA Materials Science and Technology (WP4 leader)

The ER's and ESR's employed within the work package tackle the following subjects:

Situation and summary at mid-term:

Project 8

Elisa Barisone (ESR at EMPA) optimised surface preparation techniques of steel samples based on AFM and EDX measurements and succeeded in resolving a 2 nm natural oxide film. Through several short visits at JFC the effective secondary electron emission coefficient of different conducting and insulating materials were successfully measured using the dependence of the breakdown voltage on the carrier gas pressure and electrode distance. The data received a lot of attention at the “Grenada conference”.


Project 9

At University of Oviedo a new Pulsed DC-GD source was coupled to a ToFMS instrument. The effect of GD pulse parameters on intensities of analytical signals, crater shapes and sputtering rates of conducting samples was first studied. Finally, an analytical quantification procedure based on the emission yield concept was developed for pulsed dc-GD-TOFMS and was successfully applied to the in-depth profile analysis of tinplates.

Deborah Alberts, ESR at Oviedo applied the pulsed rf-GD-OES system to thermally sensitive samples. She successfully demonstrated that pulsing can be used to avoid temperature degradation (burning) of polyurethane samples that often happen with continuous RF sources. She also investigated the effect of pulse parameters on the depth resolution using a 30 nm gold layer on a glass slide. She found that pulsing the discharge at 5 kHz frequency improves the relative depth resolution by a factor of 2 compared to continuous RF. She also paid a two-month visit to EMPA to study the time-resolved optical emission during the discharge pulse.

Project 10:
At Aqura GmbH Dr Maxim Voronov carried out investigations of possible improvements in reproducibility of analytical results in continuous DC mode using the ELEMENT GD MS instrument. He found that constant current-constant voltage mode does not improve significantly and consistently the reproducibility of the instrument. On the other hand, better results have been obtained when longer pre-sputtering times were used. He modified the GD source to use pulsed DC discharge and developed a time-gating system to allow time discrimination of ions. He investigated the discharge characteristics and analytical performance of the pulsed DC glow discharge source. Although significant improvements were expected from the time-gated pulsed glow discharge, there were no improvements in the detection limits. The analytical potential of the pulsed GD on thermally sensitive samples has been demonstrated by Dr Petr  míd. He optimised discharge conditions to study trace elements in CdTeS solar cells on glass substrate. He found that 30 to 40 data points can be recorded throughout the 2 mum thick CdTeS layer while still being able to detect trace elements.


Pr 11
Peter Horvath, ER at EMPA, and Deborah Alberts, ESR from UNIOVI studied optical emission from a pulsed RF source with sufficient time resolution to fully resolve all the features for the first time. They studied the large pre-peak observed previously on several emission lines in the first 50 mus of the RF pulse and did a comprehensive study of emission lines of Cu and surveyed several elements for other lines showing the same behaviour. Pulsed RF OES instruments can possibly take advantage of the phenomena observed. Meanwhile, Stela Canulescu, postdoc employed in the related EMDPA project has already achieved significant progress in application of the new RF-GD-ToF-MS instrument for macromolecular analysis and demonstrated together with Peter Horvath for the first time the possibility of recording negative ion spectra with the GD-MS instrument.

Project 13
At TKS Dortmund, Simone Weyler studied the effect of Hydrogen on some of those element lines which are important for the analysis of steels. In addition to iron, zinc and aluminium are very interesting in steel industry (coatings); these metals were taken as cathode materials. From the measurements, the influence of hydrogen seems to be dependent not only on the observed line but also on the matrix used. In order to eliminate molecular gas contaminants from the source, a systematic study was conducted by changing flushing and pre-sputtering times. The most significant improvement on avoiding the contamination with molecular gases can be achieved by using pre-sputtering on the sample followed by moving of the sample on the sealing ring without loosing the vacuum.

Project 12
At Tofwerk AG, Thun two prototype laser-ablation Pulsed GD-ToF-MS instruments have been constructed and are functioning. Giovanni Lotito, ESR at Tofwerk has demonstrated that the addition of post-ionization in the glow discharge to the laser ablation process results in a signal enhancement approaching an order of magnitude for metal samples measured under typical glow conditions. It was also demonstrated that the extent of fragmentation of molecular ions can be controlled with this approach. ‘Hard’ ionisation in the powered phase of the discharge results in fragmentation of the alcohol introduced into the gas phase, whereas ‘soft’ ionization in the afterglow promotes the formation of the higher mass parent molecular ion. The ability to identify the molecular origin of elements (speciation) in mass spectroscopy is of great academic interest and has immediate applications in biochemistry.

Project 14:
Antonio Martin has just (15.01.09) been hired for the post as an ER at STE. He will be studying the effects of boundary conditions on the analytical results obtained with the HR GD mass spectrometer. The research team at JFC will actively support his work at Shiva Technologies.


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September 04. 2010 13:45:50

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