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SUMMARY:‘Watching’ atoms move on atomic length and time scales with he
 lium spin echo - Dr John Ellis\, Cavendish Laboratory
DTSTART:20181017T190000Z
DTEND:20181017T200000Z
UID:TALK110944@talks.cam.ac.uk
CONTACT:Fionn Bishop
DESCRIPTION:A major scientific milestone was the advent in the early 1980
 ’s of the ability to image individual atoms\, but with it came the reali
 sation that actually what we wanted was to be able to watch them move\, ye
 t direct imaging would require framing rates of many of THz – an apparen
 tly unattainable goal. In this talk the Helium ‘spin echo’ scattering 
 technique is outlined which gives a direct handle on atomic motion at surf
 aces on the pico to nano second time scale\, and enables us to ‘watch’
  atoms move – albeit in reciprocal space and correlation time.\n\nThis e
 xperimental capability enables us to probe a wide range of atomic scale dy
 namical phenomena. Do you actually need quantum mechanics to model thermal
 ly activated motion? If you make a nano motor of a few molecules – what 
 atomic scale friction can you expect? And then the fundamental question of
  how do you work out how fast a thermally activated process occurs – til
 l now no one has been able to measure accurately enough to evaluate theore
 tical methods. The result of the test is quite telling: current theories a
 re hopelessly inaccurate\, yet their inadequacies were outlined in 1940. W
 hy does no one take any notice? Everyone just soldiers on as though blindf
 olded…
LOCATION:Wolfson Lecture Theatre\,  Department of Chemistry\, Lensfield Ro
 ad
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