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| − | = | + | = Electron Microscopy and Surface Physics - John Venables = |
== Introduction and Summary<br> == | == Introduction and Summary<br> == | ||
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This activity was a follow-op of work I had done on Ion Bombardment as a post-doc in Illinois: indeed George Thomas was an hourly worker in the Lab there, who made the courageous decision to follow me to Sussex for a PhD, courtesy of a grant from the US Air Force (who also supported David Ball). Low energy ion bombardment produces Interstitial atoms from the bombarded surface, and this was studied using Stereo-Electron Microscopy of gold containing vacancy terahedra (produced by quenching from high T as shown by John Silcox in his Cambridge PhD, now at Cornell). So the interstials migrate to the vacancy defects and cancel them out in a variety of wonderful ways, which were expected to depend on the bombardment temperature. The stereo-pictures were marvellous, and enabled depth-dependent data to be obtained. In the end we found out that the results depended on the purity of the starting material in the few ppm range, and not much on T, investigated in the range 25-283K. | This activity was a follow-op of work I had done on Ion Bombardment as a post-doc in Illinois: indeed George Thomas was an hourly worker in the Lab there, who made the courageous decision to follow me to Sussex for a PhD, courtesy of a grant from the US Air Force (who also supported David Ball). Low energy ion bombardment produces Interstitial atoms from the bombarded surface, and this was studied using Stereo-Electron Microscopy of gold containing vacancy terahedra (produced by quenching from high T as shown by John Silcox in his Cambridge PhD, now at Cornell). So the interstials migrate to the vacancy defects and cancel them out in a variety of wonderful ways, which were expected to depend on the bombardment temperature. The stereo-pictures were marvellous, and enabled depth-dependent data to be obtained. In the end we found out that the results depended on the purity of the starting material in the few ppm range, and not much on T, investigated in the range 25-283K. | ||
| − | The results contributed to ongoing sagas about Interstitials in metals, written up in a thorough paper by G.J. Thomas and myself (Phil. Mag. 28 (1973) 1171-1201). This paper was preceded by two reviews in 1969 and 1970 and several conference papers.The reviews were invited by Mike Thompson, by then well-established at Sussex and functioning as a group with Peter Townsend, Derek Palmer, Mike Lucas and their co-workers. We also made a start to measure changes in resistivity during low energy ion bombardment, but despite efforts over a couple of years, this didn't really get anywhere. Via the Harwell connections and the Atomic Collisions in Solids MSc course, we were involved in some further theses, but this area dried up as a research effort as we concentrated on the following two topics. | + | The results contributed to ongoing sagas about Interstitials in metals, written up in a thorough paper by G.J. Thomas and myself (Phil. Mag. 28 (1973) 1171-1201). This paper was preceded by two reviews in 1969 and 1970 and several conference papers.The reviews were invited by Mike Thompson, by then well-established at Sussex and functioning as a group with Peter Townsend, Derek Palmer, Mike Lucas and their co-workers. We also made a start to measure changes in resistivity during low energy ion bombardment, but despite efforts over a couple of years, this didn't really get anywhere. Via the Harwell connections and the Atomic Collisions in Solids MSc course, we were involved in some further theses, but this area dried up as a research effort as we concentrated on the following two topics. |
=== Nucleation, Growth and Defect Structure of Molecular Solids === | === Nucleation, Growth and Defect Structure of Molecular Solids === | ||
| Line 49: | Line 49: | ||
Gordon Tatlock came to Sussex from Bristol as a post-doc, and mostly established his own program on layered compounds, which he can elaborate here if he wishes. He contributed skilfully to the work of the group, including on molecular solids with Colin and Karl. This work was featured an excellent French conference in 1974 at Beaune, published in J.Phys Colloque C7 (1974) 113-119. Later still Gordon was joined by post-doc Remy Mevrel for a detailed study of twinning in the low temperature alpha-phase of solid nitrogen, published in Phil Mag 35 (1977) 641-652. Gordon has been at Liverpool University for many years as Professor of Materials Science and Engineering and is now also a staff member at the SuperStem facility at Darebury Laboratory.<br> | Gordon Tatlock came to Sussex from Bristol as a post-doc, and mostly established his own program on layered compounds, which he can elaborate here if he wishes. He contributed skilfully to the work of the group, including on molecular solids with Colin and Karl. This work was featured an excellent French conference in 1974 at Beaune, published in J.Phys Colloque C7 (1974) 113-119. Later still Gordon was joined by post-doc Remy Mevrel for a detailed study of twinning in the low temperature alpha-phase of solid nitrogen, published in Phil Mag 35 (1977) 641-652. Gordon has been at Liverpool University for many years as Professor of Materials Science and Engineering and is now also a staff member at the SuperStem facility at Darebury Laboratory.<br> | ||
| − | In the same time frame, and independent experiment was done on the vapor pressure of Ar-O2 alloys, in order to determine the hcp-fcc energy difference of Ar near its melting point. Terry Bricheno had done his PhD with Brian Smith, and we were able to get funding to study this problem using his PhD apparatus. This was one of the most satisfying results, in the sense that the method was fundamental, and the right people were in place to get the job done in a finite time. The papers are in J. Phys C 9 (1976) 4095-4108 and C10 (1977) 773-779, the latter theoretical paper with Remy as the first author. | + | In the same time frame, and independent experiment was done on the vapor pressure of Ar-O2 alloys, in order to determine the hcp-fcc energy difference of Ar near its melting point. Terry Bricheno had done his PhD with Brian Smith, and we were able to get funding to study this problem using his PhD apparatus. This was one of the most satisfying results, in the sense that the method was fundamental, and the right people were in place to get the job done in a finite time. The papers are in J. Phys C 9 (1976) 4095-4108 and C10 (1977) 773-779, the latter theoretical paper with Remy as the first author. |
=== Monolayer Phases of Adsorbed Gases on Graphite === | === Monolayer Phases of Adsorbed Gases on Graphite === | ||
| − | Michael Kramer and Garth Price arrived in Sussex in the late 1960's early 1970's from Germany and Australia respectively. They took our nucleation and growth work in a different direction, essentially by showing that the substrates David Ball and I were using could not have been clean at the monolayer level. The results we had obtained on island growth were inconsistent with the layer growth observed by other groups, notably by the French groups in Nancy and Marseille. They had studied rare gas adsorption using (Physical Chemistry) volumetric techniques, and increasingly Surface Science techniques. As we started to correspond with them, we realized that there was a huge literature out there, and a visit was in order. <br> | + | Michael Kramer and Garth Price arrived in Sussex in the late 1960's early 1970's from Germany and Australia respectively. They took our nucleation and growth work in a different direction, essentially by showing that the substrates David Ball and I were using could not have been clean at the monolayer level. The results we had obtained on island growth were inconsistent with the layer growth observed by other groups, notably by the French groups in Nancy and Marseille. They had studied rare gas adsorption using (Physical Chemistry) volumetric techniques, and increasingly Surface Science techniques. As we started to correspond with them, we realized that there was a huge literature out there, and a visit was in order. <br> |
== Research Activity 2: Ultra-high Vacuum Scanning Electron Microsocopy == | == Research Activity 2: Ultra-high Vacuum Scanning Electron Microsocopy == | ||
Revision as of 10:41, 18 September 2011
Contents
- 1 Electron Microscopy and Surface Physics - John Venables
Electron Microscopy and Surface Physics - John Venables
Introduction and Summary
Sussex Physics was a wonderful place to get a first "proper job". After a PhD in Cambridge and a 3-year post-doc period in Illinois, it was great to have an exciting new job, and to return to a beautiful and vibrant part of the UK. I wish to pay tribute to Ken Smith, our foundation Professor of Experimental Physics. It was Ken who appointed me to Sussex in the Autumn term of 1994. I had known Ken in Cambridge, where I assisted in his Part II Physics Laboratory as a graduate student. Work on Electron Microscopy was very strong in Peter Hirsch's Metal Physics group [1], and so I was able to get a post-doc position in the USA at the University of Illinois, and then join Sussex at a formative stage.
This page is about the Electron Microscopy and Surface Physics research group at Sussex. We were not isolated in our interests, but had overlaps with the group on Particle-Solid interactions and also with other efforts in Condensed Matter Physics, Low Temperature Physics and Materials Science. Michael Thompson and Robert Cahn were both appointed to Professorships in 1965, in Physics and Materials Science respectively. These appointments and those that followed greatly increased the possibilities for collaboration, both in research and graduate level and specialist undergraduate teaching across departmental lines. And, although we were passionate about our Science and research in particular, Sussex was a place where many other activities, especially of an interdisciplinary nature, were encouraged.
Sussex literally gave me, and by extension all of us, a chance to do my "own thing", and I feel very grateful to have been able to take that, and build on it in my/our own way. The "our" is important of course, since without collaborators, technical help, students and especially graduate students, one can do very little in experimental physics or any other experimental science. I have been particularly fortunate in all these aspects: the fact that we had an excellent Mechanical Workshop under Frank Schofield made all sorts of technical developments in Transmission Electron Microscopy possible from the start. Later, we also used the staff of the Electronics Workshop as well, to keep ahead of developments in Scanning Electron Microscopy. Some of these aspects will be described in the two sections that follow
One of the great possibilities offered by this Wiki form of history, is that all of our collaborators can contribute whatever they want or have time for. I am still very much in contact with one of my two first graduate students, George J. Thomas, and the other David J. Ball, can be found via a simple Google searches. Both have had distinguished careers in the US National Laboratory system, and as a Professor/Consultant on Risk Management in the UK respectively. My long-term technician, Chris Harland, who subequently got a PhD himself, and after spells in Industry, became Reader in Electronics at Sussex.
I am not planning to transfer the group publication list to this site, since there is already a complete list on my Arizona State University site [2]. I retired from Sussex in January 1995, but have been associated with the University since as an Honorary Professor, and currently as Emeritus Professor. The list of group members ends at 1995, but that is not the end of the story: Michael Hardiman, Senior Lecturer in Physics, continues research but in a somewhat different field. I have continued research in Arizona, at the London Centre for Nanotechnology at UCL, and with several colleagues around the world.
I look forward to possibly remaking contact with several other former co-workers via this celebration of Sussex@50. If any of you wish to elaborate on my account here, that will be wonderful.
References
1. Members of the Metal Physics group were much in demand worldwide at the time, and produced the "Bible", Electron Microscopy of Thin Crystals (Butterworths, London, 1965) following a succesful summer school in July 1963. The authors, P. B. Hirsch FRS, A. Howie, R.B Nicholson, D.W. Pashley and M.J. Whelan, all be came very well known for a whole "School" of Electron Microscopy that spread round the world. The authors went on to lead groups in Oxford (Professor Sir Peter Hirsch and Professor Mike Whelan, FRS), Cambridge (Professor Archie Howie, CBE, FRS), Imperial College (Professor Don Pashley, FRS). Sir Robin Nicholson FRS, FREng was Chief Scientific Advisor, Cabinet Office from 1983-1985 during a long career in Industry and Academia.
2. Since 1985 I have been a Professor at Arizona State University in the Physics Department on a part-time basis. There I maintain a home page, which contains all my professional details, including teaching, research, publcations and short-form CV.
Research Activity 1: In-situ Transmission Electron Microscopy
Shortly after my arrival in Sussex, Professor Ken Smith signed a purchase order for a Hitachi HU 11B Electron Microscope. This was for £11, 600 or thereabouts, a large sum of money in 1964: but of course without a microscope we could do nothing. This instrument became the workhorse of the early years of the group, and it got heavily modified, several times, in the process. I had decided to try my hand at what became known as In-situ Microscopy: performing experiments on the samples inside the microscope and observing them at the same time, or shortly afterwards with out breaking the vacuum.
In particular, we constructed a variable temperature stage that was cooled by liquid helium. Liquid helium was in more or less plentiful supply at Sussex from early on, due to the presence in the Department of the Low Temperature group. The Mechanical Workshop staff were crucial in the fine scale machining needed to make several versions of the low temperature stages and accessories over a long period
With my first two graduate students, we started on our first two scientific topics, outlined below: "Electron microscopy of low energy ion damage in Metals" with George Thomas (DPhil 1969), and "Nucleation, growth and defect structure of Rare Gas Solids" with David Ball (D.Phil 1969). The first project involved construction a removable low energy ion gun to fit above the stage. The second involved various cells and directed gas beams to grow the crystals at well defined pressures and temperatures. While the projects started out in an exploratory manner, they nearly all became quantitative studies with T and p (and ion current) as the independant variables.
This (thermodynamic) motivation became particularly important later on, when the aging microscope was converted into a high precision diffraction camera. It was used to study the monolayer phases of rare gases adsorbed on graphite with high precision. The microscope and surrounding equipment is shown in this latest incarnation in Figure 1 below. The schematic diagram of what is essentially going on in the neighbourhood of the thin film sample is shown in Figure 2 (below right). For more details the relevant theses and publciations can be consulted, but for now, a lot of good work was accomplished on this machine by quite a few graduate students, post-docs, visitors and technical staff. Indeed I enjoyed taking some interesting pictures and diffraction patterns myself...
Low Energy Ion Damage in Metals
This activity was a follow-op of work I had done on Ion Bombardment as a post-doc in Illinois: indeed George Thomas was an hourly worker in the Lab there, who made the courageous decision to follow me to Sussex for a PhD, courtesy of a grant from the US Air Force (who also supported David Ball). Low energy ion bombardment produces Interstitial atoms from the bombarded surface, and this was studied using Stereo-Electron Microscopy of gold containing vacancy terahedra (produced by quenching from high T as shown by John Silcox in his Cambridge PhD, now at Cornell). So the interstials migrate to the vacancy defects and cancel them out in a variety of wonderful ways, which were expected to depend on the bombardment temperature. The stereo-pictures were marvellous, and enabled depth-dependent data to be obtained. In the end we found out that the results depended on the purity of the starting material in the few ppm range, and not much on T, investigated in the range 25-283K.
The results contributed to ongoing sagas about Interstitials in metals, written up in a thorough paper by G.J. Thomas and myself (Phil. Mag. 28 (1973) 1171-1201). This paper was preceded by two reviews in 1969 and 1970 and several conference papers.The reviews were invited by Mike Thompson, by then well-established at Sussex and functioning as a group with Peter Townsend, Derek Palmer, Mike Lucas and their co-workers. We also made a start to measure changes in resistivity during low energy ion bombardment, but despite efforts over a couple of years, this didn't really get anywhere. Via the Harwell connections and the Atomic Collisions in Solids MSc course, we were involved in some further theses, but this area dried up as a research effort as we concentrated on the following two topics.
Nucleation, Growth and Defect Structure of Molecular Solids
The work started with David Ball on rare gas solids developed rapidly and in a number of exciting ways. By growing the crystals on graphite at different T and p, we found the type of behaviour expected for nucleation and growth on surfaces; this started an interest in Nucleation and Growth kinetics which has persisted to the present day. David's work was written up in several places, perhaps most prestigiously in Proceedings of the Royal Society A 322 (1971) 331-354. We used the review of Nucleation and Growth that visiting faculty member Dan Frankl and I wrote for Advances in Physics 19 (1970) 409-456 to interpret the results and compare with the theory of rare gas interatomic, and rare gas-graphite potentials. The microstructure of the rare gas crystals, and dislocations in these crystals, were also studied in some detail.
Before long, David was joined by further graduate students Colin English, Karl Niebel and post-doc Gordon Tatlock, who followed up on his work and took it in new directions. Colin branched out to other "simple" molecular solids, N2, O2, etc and we produced some wonderful microscopy, as shown in Figure 3 for alpha-N2, as well as solving long-standing questions about the crystal structure and twinning in these diatomic molecular solids. This work was published initially in Phil Mag 21 (1970) 147-166 with a review in Thin Solid Films 7 (1971) 369-389, and then in Acta Cryst. B30 (1974) 929-935 In parallel, Colin (Dhil Thesis, 1974) studied a simple model of the diatomic solids, Proc. Roy. Soc. A340 (1974) 57-80 and 81-90, the latter with Dennis Salahub. Dennis was then John Murrell's post-doc, and subsequently Professor in Montreal. After a post-doc period in our group in Sussex, Colin moved to Harwell (AEA Technology) Harwell, and is now a Visiting Professor at Oxford.
Gordon Tatlock came to Sussex from Bristol as a post-doc, and mostly established his own program on layered compounds, which he can elaborate here if he wishes. He contributed skilfully to the work of the group, including on molecular solids with Colin and Karl. This work was featured an excellent French conference in 1974 at Beaune, published in J.Phys Colloque C7 (1974) 113-119. Later still Gordon was joined by post-doc Remy Mevrel for a detailed study of twinning in the low temperature alpha-phase of solid nitrogen, published in Phil Mag 35 (1977) 641-652. Gordon has been at Liverpool University for many years as Professor of Materials Science and Engineering and is now also a staff member at the SuperStem facility at Darebury Laboratory.
In the same time frame, and independent experiment was done on the vapor pressure of Ar-O2 alloys, in order to determine the hcp-fcc energy difference of Ar near its melting point. Terry Bricheno had done his PhD with Brian Smith, and we were able to get funding to study this problem using his PhD apparatus. This was one of the most satisfying results, in the sense that the method was fundamental, and the right people were in place to get the job done in a finite time. The papers are in J. Phys C 9 (1976) 4095-4108 and C10 (1977) 773-779, the latter theoretical paper with Remy as the first author.
Monolayer Phases of Adsorbed Gases on Graphite
Michael Kramer and Garth Price arrived in Sussex in the late 1960's early 1970's from Germany and Australia respectively. They took our nucleation and growth work in a different direction, essentially by showing that the substrates David Ball and I were using could not have been clean at the monolayer level. The results we had obtained on island growth were inconsistent with the layer growth observed by other groups, notably by the French groups in Nancy and Marseille. They had studied rare gas adsorption using (Physical Chemistry) volumetric techniques, and increasingly Surface Science techniques. As we started to correspond with them, we realized that there was a huge literature out there, and a visit was in order.
Research Activity 2: Ultra-high Vacuum Scanning Electron Microsocopy
Research Activity 3: Related Theoretical and Computational Studies
Appendix: Group Members
This list includes all categories of colleagues in approximate historical order (of starting), and is not at present complete. I would like to hear of omissions.
The abreviations are: Faculty associated with the group, even if loosly (F), Graduate Student (GS); Research Fellow (RF), Technical Staff (TS), Visiting Faculty (VF), Visiting Researcher (VR), Visiting and Exchange Student (VE), Project Student (PS), typically for a final year project.
Names, graduation dates and thesis titles for Physics D.Phil and M. Phil students are given in the list on this site.
There is no detail on the source of funding for anyone person or project, since this typically changed with time.
1964-1969
For thesis dates and titles click Research-dphil_p_by_year_early
John A. Venables (F)
George J. Thomas (GS)
David J. Ball (GS)
John S. Notton (TS)
Henry R. Gylde (RF with Brian Smith)
Daniel R. Frankl (VF- Professor, Pennsylvania State University)
Dirk van Vliet (RF)
Colin A. English (GS)
H. Michael Kramer (GS)
Keith Davies (TS)
1970-1979
For thesis dates and titles click here
Christopher J. Harland (TS)
Barrie W. Griffiths (GS)
Karl F. Niebel (GS)
Klaus H. Ecker (GS)
Garth L. Price (GS)
Gordon J. Tatlock (RF)
Ramli Bin-Jaya (GS, MSc student)
Adrian P. Janssen (RF)
Bruce A. Joyce (VF, Group leader at Mullards/ Phillips Redhil)
Terry E. Bricheno (RF, also GS with Brian Smith)
Michel Bienfait (VF, Professor at Aix-Marseille II)
Jonathan H. Klein (GS, MSc student)
Remy Mevrel (RF)
George S. Samuel (GS)
Pablo Schabes-Retchkiman (GS)
Klaus Hartig (VR, Research student at Bochum)
Parvez Akhter (GS)
Jacques Derrien (VF, Professor at Aix-Marseille II)
Gary D. Archer (GS, MSc student)
Jeff Spain (TS)
Arthur C. Sinnock (VF with Brian Smith, Brighton Polytechnic)
1980-1989
For thesis dates and titles click here
Geoff D.T. Spiller (RF)
Graeme Raynerd (GS, then RF)
Jean Suzanne (VF, Professor at Aix-Marseille II)
David J. Fathers (RF)
Michael Hardiman (F, "New Blood" Lecturer from 1983)
Jean-Jacques Metois (VF, CRMC2-CNRS Marseille)
Ludwig W. Bruch (VF, University of Wisconsin)
Margrit Hanbücken (RF)
Jean-Marie Bermond (VF, Professor at Aix-Marseille III)
Robert J. Keyse (GS)
David R. Batchelor (GS)
Masaaki Futamoto (VR, Hitachi Central Laboratories, Tokyo)
Gareth W. Jones (GS)
Oladipo (Ladi) Osasona (VR, Universiy of Ile-Ife, Nigeria)
Abdul-Qader D. Faisal (GS)
Marilyn Whitehouse-Yeo (TS)
Mohamed Alikacem (GS, MSc student)
Mohamed Hamichi (GS)
Albert E. Curzon (VF, Professor at Simon Fraser University, Burnaby, BC)
Gerhard Cox (GS, MSc student, and Diplom 1986, RWTH, Aachen)
Timothy Doust (GS)
Robert Kariotis (RF)
Parmjit S. Flora (GS)
Min Huang (GS)
Frances L. Metcalfe (GS)
1990-1995
For thesis dates and titles click here
Jesus M. Marcano (RF)
E. Hoffman (VE)
Pontus Stenström (VE, 1991)
Robert H. Milne (F, 5-year fixed term Lecturer from ?)
Mohamed Azim (GS with Bob Milne)
Michael Stumpf (VE, 1993)
Örjan Bodin (VE, 1993)
T. J. Martin (PS? with Bob Milne)
T.E. Amine Zerrouk (GS)
Raj Persaud (RF)
Hisato Noro (GS)
Akira Sugawara (VR from Japan and Arizona State)