Meeting Report
University of Surrey
Thursday 5th January 1995
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Page 1. A talk by Prof. Jim Matthew (University of York) on the
development of out knowledge and appreciation of chemical shifts in XPS and AES. (56k)
Page 2. Continued from page 1. (69k)
Page 3.A talk by Martin Seah (NPL/DTI) on the use of surface analysis
to provide well known physical parameters such as refractive index, surface energy and
work of fracture. Also a talk by Jim Castle (University of Surrey) on getting as much as
possible out of XPS results and means of interpretation which can be used by
nonspecialists. (63k)
Page 4. Continued from Page 3, also a talk by Peter Weightman (IRC,
Liverpool) on the calculation of a new scale of electronegativity. (74k)
Page 5. Continued from page 4. (37k)
The afternoon session was dedicated to workshops.
| Leader |
Bob Wild (IAC, Bristol) |
| Raporteur |
Alison Taylor (University of Surrey) |
Bob outlined the operation of two ISO TC 201 & BSI C1160 standards
committees. Members of the UK Surface Analysis Forum are closely involved with these committees
and the existence of the Group has helped in formulating a coherent UK response to various
proposed standards. The aim of the workshop was to gather points of view from both
manufacturers and customers regarding what they require from instrument standardisation.
John Watts is currently collating data from manufacturers.
The potential merits of standardisation were recognised by everyone
although, in the past, manufacturers had presented performance indicators derived from
nonstandard methods. Deciding which parameters should be presented to customers was a
potential problem. Outline specifications for discussion were thought too detailed and
there were cost implications in terms of time in test. It was therefore agreed that a list
of key parameters should be produced with a procedure for measuring them. The intensity
and energy resolution on the Ag3d peak were accepted parameters but S/N and S/B were still
being debated. Any list of parameters could be added to subsequently but the important
aspect is that they are obtained using a standard procedure.
Actions from the meeting were 1 ) John Watts to collate manufacturers
specification sheets and produce a summary, 2) John and Bob will begin to draft standard
procedures for obtaining key parameters for discussion at the next BSI meeting in April
1995.
| Leader & Raporteur |
Len Hazell |
This workshop began with a review of the theory and how soon it will be
of direct practical value in analysis. The combination of work in Groups at Liverpool and
York is in the vanguard of calculating chemical shifts. The ultimate aim is to be able to
calculate the peak position of a given molecular structure and vice versa However there
are still some unknowns and application to complex systems is unlikely for some years.
There was an extended discussion of the practical problems in
measurement of chemical shifts. This ranged over 1 ) the prob!ems of sample charging,
particularly with monochromators, 2) the need for background subtraction and curve
resolving, 3) whether knowledge of the spectrometer performance could be used to assess
the peak widths for curve resolving (answer NO!) and 4) the use of combined XPS/AES shifts
in the form of the Auger parameter. The conclusions were that, as analysts, we were doing
the right sorts of things and nothing fundamentally new had been introduced for many years
now. There was an appeal for a single button fully compensating charge neutralisation
system for use with the greatly improved specification monochromators now available.
Most elements possessed useful chemical shifts but interpretation
depended on published literature, home grown reference compounds (mostly not easy to
generate) and databases. Unfortunately, the precision of data in available databases is
variable because the original data was not acquired under accredited conditions. This may
be an area that will have to be readdressed after accreditation status has been achieved
by a larger number of Groups.
The benefit of the workshop was that members had gained a better
appreciation of the meaning, value and necessary acquisition strategy for measuring
chemical shifts but it was disappointing to realise how much more needs to be done before
theory can help us identify compounds on surfaces.
| Leader |
Albert Carley |
| Raporteur |
Martin Seah |
This workshop was carefully structured to consider the overall purpose
of data systems, the problems of upgrades as equipments ages, essential developments for
future data systems and possible directions for the future.
Data systems are used for both acquisition and data processing. In most
cases the analysis time could be used more effectively. Aging data systems were difficult
to support and need to be replaced eventually. There was now a healthy competitive
environment with the availability of third party systems.
Users would like to see increased intelligence and automation to (1)
relieve expert staff of slow repetitive tasks and (2) to ensure that all analysts could
work to the best practice standard of the experts users. Increased automation, either to a
user's recipe or an approved standard, would be welcomed. Data integrity had to be
maintained and the recipe documented with the data file. The validation of software
routines become more and more important as the complexity increases. Aspects of peak
deconvolution, reconstruction of depth profiles from angle-resolved data, maximum entropy
processing, error analysis and quantification were discussed.
The above list of items showed that data processing software needed
continual upgrading whereas the acquisition software only needed periodic revision. One
useful way of allowing upgrades was to adopt a modular approach where user defined
activities can be built around a general platform such as MATLAB. Tracking of version
numbers and validation is essential however.
Five main concepts for processing software featured repeatedly
throughout the discussion, Automation, Flexibility, Modularity, Upgradability and
Validation. Standardisation, used effectively to generate best practice recommendations
and checking routines could promote this; used ineffectively, it could become a
straightjacket. |
