IJS KOLOKVIJ, sreda, 16. 09. 2015; ob 13. uri; prof. dr. Steven L. Johnson

[Tanja Debevec]

Vabimo vas na 1. predavanje iz sklopa "Kolokviji na IJS" v letu 2015/16, ki bo v sredo, 16. septembra 2015, ob 13. uri v Veliki predavalnici Instituta »Jožef Stefan«  na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete tudi na naslovu http://www.ijs.si/ijsw/Koledar_prireditev, posnetke preteklih predavanj pa na http://videolectures.net/kolokviji_ijs. 

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prof. dr.  Steven L. Johnson

Inštitut za kvantno elektroniko, ETH Zurich, Švica

 

 

Nadzirati zgradbo snovi na atomski ravni s svetlobo

 

Stara zamisel, da bi z močnimi kratkimi pulzi svetlobe reverzibilno nadzirali strukturo kondenzirane snovi, je zanimiva z vidika uporabe in je obenem temeljni izziv na področju močno neravnovesnih lastnosti materialov. Celovita eksperimentalna raziskava tega vprašanja zahteva hkraten razvoj močnih kontrolnih pulzov posebne oblike ter karseda neposrednih načinov merjenja učinka teh pulzov na strukturo in na dinamiko v izbranem materialu. Predstavili bomo več izbranih primerov ekscitacij snovi s svetlobo, ki jih je mogoče kvantitativno raziskati s časovno ločljivim sipanjem rentgenskih žarkov. Primere je moč razdeliti na dve skupini. V prvi so tisti, kjer vzbujamo dinamiko dolgovalovnega strukturnega reda s svetlobo iz bližnjega infrardečega spektra preko elektronskih prehodov, v drugi tisti, kjer z dolgovalovnim teraherčnim sevanjem neposredno vzbujamo električno aktivne kolektivne strukturne načine kristalne mreže in/ali spinskih sistemov. Predavanje bomo sklenili s pregledom moznosti, da bi s temi metodami reverzibilno preklapljali domene v feroelektrikih in multiferoikih.

Predavanje bo v angleščini.

Lepo vabljeni!

 

 

 




We invite you to the 1th Institute colloquium in the academic year 2015/16. The colloquium will be held on Wednesday September 16, 2015 at 1 PM in the main Institute lecture hall, Jamova 39, Ljubljana. To read the abstract click  http://www.ijs.si/ijsw/Koledar_prireditev. Past colloquia are posted on  http://videolectures.net/kolokviji_ijs.

 

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prof. dr.  Steven L. Johnson 

Institute of Quantum Electronics, ETH Zurich, Switzerland

 

 

Driving Atomic-Scale Structure with Light

 

The long-standing idea of using intense, short light pulses as a means of reversibly controlling the structure of condensed matter systems holds interest from an applications perspective and additionally serves as a fundamental challenge for understanding the strongly out-of-equilibrium properties of materials.  A complete experimental approach to this problem requires simultaneous development of tailored high-intensity “control” light pulses as well as a means of measuring as directly as possible the influence of these pulses on the structure and dynamics of a particular material.  Here we discuss several representative examples of light-driven structural excitations that are quantitatively characterized using time-resolved x-ray diffraction.  These examples fall roughly into two categories.  The first category uses light at near-optical wavelengths to indirectly excite dynamics of long-range structural order via electronic transitions.  The second category of examples involves using long-wavelength, THz-frequency radiation to directly excite electric-dipole active collective structural modes of the lattice and/or spin systems.  We conclude with an outlook on the future potential of these methods to achieve reversible control over domains in ferroelectrics and multiferroics.

 

Cordially invited!

 

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