Materials Research Activities

History of Scanning Probe Microscopy in Denmark

History of Scanning Probe Microscopy in Denmark

The history of the new and highly successful family of instruments termed scanning probe microscopes (SPMs) is a complex one, primarily because they are being used in a great many and diverse fields. The history in a small country such as Denmark is much less complex and consequently easier both to tell and to follow. The Danish story is representative of developments across the institutional board: universities, private enterprise, and quasi-governmental metrology. And yet, it remains a small world, where a handful of individuals all know each other. The story may be summarized as academic success and the promise of commercial success in data analysis software combined with comparative failure in the commercial development of hardware.

Guide to acronyms:

  • AU: Aarhus University
  • CAMP: Center for Atomic-Scale Physics
  • DFM: Danish Institute of Fundamental Metrology
  • DME: Danish Micro-Engineering
  • DTU: Danish Technical University
  • SPM: Scanning Probe Microscope
  • STM: Scanning Tunneling Microscope

The history of scanning probe microscopy in Denmark begins in the summer of 1987, some six months after the Nobel Prize in physics had been awarded to Gerd Binnig and Heinrich Rohrer for their invention of the scanning tunneling microscope (for a technical introduction to the STM and its variants, now classed under the heading SPM, click here). A group around Flemming Besenbacher at Aarhus University's Department of Physics and Astronomy, some of whom had worked on surface science topics, were impressed with the promise of the STM in this field. Since STMs could not yet be purchased (Digital Instruments, as the first company, began to sell STMs in 1989), they (in particular Erik Lægsgaard) built one themselves in a matter of a month or so. This instrument has turned out to be highly successful within the academic sphere. The Aarhus group has produced a long string of publications on many topics, such as surface reconstruction, movie visualization of surface diffusion, and the design of catalysts based on STM analyses. From 1993 onwards, a government-funded project, Center for Atomic-Scale Materials Physics (CAMP), has provided the institutional framework using STMs to investigate metallic surfaces.

The personal connections within the Danish world of scanning probe microscopy are tight, as one might expect of a small country. CAMP was set up as a collaboration of a theoretical group at the Danish Technical University in Lyngby, a Copenhagen suburb, and an experimental one at the University of Aarhus, Denmark's second city. (The latter group also supports seven PhD students.) Jens Nørskov (DTU) and Flemming Besenbacher (AU) had already published together since 1982. The DTU group is located in the same building as the Danish Institute of Fundamental Metrology (DFM) that provides SPM-based expertise to private enterprise. Jørgen Garnæs, who is in charge of DFM's SPM work, also published with the Aarhus group in the early 1990s. In the late 1980s, there was an initiative for a commercial venture based on the proven Aarhus STM-design by the Copenhagen-based company Danish Micro Engineering. In this context, extensive consultations took place between DME and the Aarhus group and patents were filed. This venture might be considered a failure given Denmark's traditional strength in small-scale precision engineering and the opportunity to win a captive and quickly growing customer group. DME did not establish a market presence before Digital Instruments took a market lead that the Californian company has held ever since. DME still manufactures and sells SPMs, but its share of the market is very small. The personal connections are also obvious in the case of Jan Friis Jørgensen, who worked briefly at DME (1989-1990) and subsequently held a position at DFM (1993-1995, 1996-1998) before setting up his own company, Image Metrology, that has developed what is probably the most widely used SPM software: the Scanning Probe Image Processor. Image Metrology also has some of its offices in the very building of DFM and CAMP-Lyngby.

The Danish SPM world is thus small and closely knit. But the above paragraph might exaggerate this aspect. There are other scientists using SPMs who move in different circles, such as Jens E. T. Andersen, who uses STMs to do electrochemical research, "in-situ STM". True, he also works at the DTU, a stone's throw from the DFM/CAMP-Lyngby/Image Metrology building, but his interests and connections are different. The Danish SPM world is also not as insular as the previous paragraph might indicate. Many of the individuals have spent significant periods of time abroad. Ivan Steensgaard of CAMP-Aarhus worked at the Bell Labs, Murray Hill, from 1977 to 1979 - in addition to teaching at the Dar es Salam Technical College in Tanzania from 1971 to 1973. Jørgen Garnæs spent a year (1991-2) at the University of California at Santa Barbara working on SPM investigations of thin organic and Langmuir-Blodgett films. Jan Friis Jørgensen has spent four months at IBM Zurich, where the STM was invented, and a year at the National Institute of Science and Technology just outside Washington D.C. DFM participates in a project sponsored by the European Union on SPM-related standards. Other participants in the project include most of the national metrological institutions in other European countries.

Danish SPM researchers all know each other and they are internationally connected. There are now even endeavours afoot to establish a large nanotechnology project modelled on the US National Nanotechnology Initiative. But given the smallness of the Danish community, there are many aspects of SPM history that cannot be illustrated with the Danish case. The academic activities are limited to metals (and electrochemistry) whereas elsewhere the use of SPMs in semiconductor research and even production takes center stage. There is also only little work done in Denmark to push the use of SPMs into life science research and data storage. The focus has also very much been on the STM and not so much on research on and with other SPMs, such as the Atomic Force Microscope. Nonetheless, the Danish case can yield a rough chronology of SPM-related research that is a good guide to international developments:

  • 1987: first use of an STM
  • 1988: first academic and commercial activities
  • 1989-1992:
    • loss of commercial market to Californian companies
    • successful academic research (1990: diffusion movies)
    • metrological infrastructure beginning
  • 1993: medium-term academic funding secured
  • 1994: STM first applied to catalysis research
  • 1995: in-situ STM research takes off
  • 1996: international metrological collaboration begins
  • 1997: nanowires and quantum effects

This page was last updated on 9 February 2004 by Arne Hessenbruch