IJS KOLOKVIJ, sreda, 21. 4. 2021, ob 13. uri, prof. dr. Claudio Masciovecchio

Fri Apr 16 23:27:59 CEST 2021

Vabimo vas na 5. predavanje iz sklopa "Kolokviji na IJS" v letu 2020/21, ki bo 21. aprila 2021, ob 13. uri. Predavanje bo v spletnem konferenčnem sistemu Zoom in mu lahko prisostvujete tako, da v brskalnik prenesete naslov  <https://uni-lj-si.zoom.us/j/98099345188?pwd=c1M0dHdnNHVDVFc2aC90RktCUHJKUT09> https://uni-lj-si.zoom.us/j/98099345188?pwd=c1M0dHdnNHVDVFc2aC90RktCUHJKUT09; identifikacijska stevilka sestanka je 980 9934 5188, geslo pa 876849.

Predavanje lahko spremljate tudi na TV IJS kanalu na spletnem naslovu  <http://tv.ijs.si> tv.ijs.si.

Napovednik predavanja najdete na naslovu  <http://www.ijs.si/ijsw/Koledar_prireditev> http://www.ijs.si/ijsw/Koledar_prireditev, posnetke preteklih predavanj pa na  <http://videolectures.net/kolokviji_ijs> http://videolectures.net/kolokviji_ijs.

prof. dr. Claudio Masciovecchio

Elettra Sincrotrone Trieste, Trst, Italija 

Nove možnosti raziskav z laserjem na proste elektrone 

V predavanju bomo opisali, kako je nedavni razvoj zmogljivosti laserjev na proste elektrone omogočil nelinearne eksperimente pri suboptičnih valovnih dolžnah. Posebej eksperimenti s podvajanjem frekvence (SHG) in tranzientno mrežico so končno prikazali velik potencial tehnik vakuumskega mešanja ultravijolične in mehke rentgenske svetlobe. Podvajanje frekvence je eden od nelinearnih odzivov sistema, ki je prisoten le v materialih brez centra simetrije, kot so površine ali gladine. Prednosti uporabe elektronske resonance prinesejo znatno večjo površinsko specificnost kot obstoječe metode, ki slonijo na mehkih rentgenskih žarkih. Eksperimenti s tranzientno mrežico pri suboptičnih valovnih dolžinah so primerni za raziskave dinamike razurejenih sistemov in polprevodnikov na nanoskali. Z vzbujanjem fononov z nanometrsko valovno dolžino bi lahko razjasnili vrsto odprtih znanstvenih vprašanj od termičnih anomalij v steklih do transporta toplote na nanoskali. Prav raziskave transporta toplote na nanoskali so izjemnega pomena za potrebe tehnologije kot je npr. nadzor toplote pri elektronskih napravah. Mešanje mehkih rentgenskih žarkov pa lahko uporabimo za študij medmolekularne vibracijske dinamike pri zdravilnih učinkovinah in pri tarčah, preko katere bi lahko razumeli značilne razlike v biološki aktivnosti enantiomerov, ali za spremljanje dinamike kovinskih kompleksov. 

[1]   R. K. Lam et al., Phys. Rev. Lett. 120, 023901 (2018).

[2]   F. Bencivenga et al., Adv. Phys. 63, 327 (2015).

[3]   F. Bencivenga et al., Sci. Adv. 5, 5805, (2019).

[4]   R. Mincigrucci et al., submitted.

Predavanje bo v angleščini.

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We invite you to the 5th Institute colloquium in the academic year 2020/21. The colloquium will be held on Wednesday April 21, 2021 at 1 PM. The colloquium will be organized online using the zoom conference platform. To attend the colloquium, please copy the  <https://uni-lj-si.zoom.us/j/98099345188?pwd=c1M0dHdnNHVDVFc2aC90RktCUHJKUT09> https://uni-lj-si.zoom.us/j/98099345188?pwd=c1M0dHdnNHVDVFc2aC90RktCUHJKUT09; meeting ID is 980 9934 5188, password is 876849.

To read the abstract click   <http://www.ijs.si/ijsw/Koledar_prireditev> http://www.ijs.si/ijsw/Koledar_prireditev. Past colloquia are posted on   <http://videolectures.net/kolokviji_ijs> http://videolectures.net/kolokviji_ijs.

prof. dr. Claudio Masciovecchio 

Eletrra Sincrotrone Trieste, Trieste, Italy

New research opportunities with free electron lasers

In this talk, we will discuss how recent advances in the performance of the free electron lasers (FELs) allowed non-linear experiments at sub-optical wavelengths. In particular second harmonic generation (SHG) and transient grating (TG) experiments have finally demonstrated the high potential of vacuum ultraviolet/soft X-ray wave mixing techniques. SHG is one of the second-order non-linear responses of systems that are non-zero only for non-centrosymmetric materials as surfaces or interfaces. The advantages of using electronic resonance would imply a significantly higher surface specificity than existing soft X-ray methods. TG experiments at sub-optical wavelength are relevant for the study of nanoscale dynamics in disordered systems as well as in semiconductors. Exciting phonon modes with nanometer wavelength would allow shedding light on a plethora of scientific open problems ranging from the thermal anomalies in glasses to understanding nanoscale thermal transport. Indeed, the study of thermal transport approaching the nanometer is extremely important and motivated by relevant technological needs such as thermal management of electronic devices. Wave mixing in the soft X-ray can be used as well to investigate drug/target intermolecular vibrational dynamics, possessing the potential to understand the marked differences in biological activities of enantiomers, or easily follow the dynamics of metal complexes.

[1] R. K. Lam et al., Phys. Rev. Lett. 120, 023901 (2018).

[2] F. Bencivenga et al., Adv. Phys. 63, 327 (2015).

[3] F. Bencivenga et al., Sci. Adv. 5, 5805, (2019).

[4] R. Mincigrucci et al., submitted.

Cordially invited!

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