BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-1007
DTSTART:20080129T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260423T072134Z
LAST-MODIFIED:19700101T060000Z
LOCATION:5310 Chamberlin Hall
SUMMARY:Femtosecond Electron Diffraction:'Making the Molecular Movie'\
 , R. G. Herb Condensed Matter Seminar\, Dwayne Miller Chemistry and Ph
 ysics University of Tornonto
DESCRIPTION:Femtosecond Electron Diffraction harbours great potential 
 for providing atomic resolution to structural changes as they occur\, 
 essentially watching atoms move in real time directly observe transiti
 on states. This experiment has been referred to as 'making the molecul
 ar movie' and has been previously discussed in the context of a classi
 c gedanken experiment\, outside the realm of direct observation. With 
 the recent development of femtosecond electron pulses with sufficient 
 number density to execute nearly single shot structure determinations\
 , this experiment has been finally realized. A new concept in electron
  pulse generation was developed based on a solution to the N-body elec
 tron propagation problem involving up to 10\,000 interacting electrons
  that has led to a new generation of extremely bright electron pulsed 
 sources that minimizes space charge broadening effects. Previously tho
 ught intractable problems of determining t=0 and fully characterizing 
 electron pulses on the femtosecond time scale have now been solved thr
 ough the use of the laser pondermotive potential to provide a time dep
 endent scattering source. Synchronization of electron probe and laser 
 excitation pulses is now possible with an accuracy of 10 femtoseconds 
 to follow even the fastest nuclear motions. The camera for the 'molecu
 lar movie' is now in hand. Atomic level views of the simplest possible
  structural transition\, melting\, have been obtained for a number of 
 metals under strongly driven conditions (up to warm dense matter condi
 tions) under which the dynamics occur over nm or molecular lengths sca
 les. Direct observation of phonon distortions involved in electron-sca
 ttering and electronically driven structure changes in Si can now be r
 esolved. Applications to specific molecular systems will also be discu
 ssed in the context of directly imaging reaction dynamics at the atomi
 c level of inspection.
URL:https://www.physics.wisc.edu/events/?id=1007
END:VEVENT
END:VCALENDAR