[institut] Center for Solid State Physics and New Materials Seminar - Wednesday, November 1st 2017 at 13:00 h

[Nenad Lazarevic]

Поштоване колегинице и колеге,

Са задовољством вас позивам на семинар Центра за физику чврстог стања и 
нове материјале, под насловом

„Optical properties of WS2 nanotubes”.

који ће одржати др Бојана Вишић из Института Јожеф Стефан, Словенија и 
Вајцман института, Израел. Семинар ће се одржати у читаоници Института 
за физику „Др Драган Поповић“, у среду 1. новембра 2017. године, са 
почетком у 13 часова.

Срдачан поздрав,
Ненад Лазаревић


Dear Colleagues,

It is my pleasure to invite you to the Center for Solid State Physics 
and New Materials Seminar entitled

„Optical properties of WS2 nanotubes”

which will be given by Dr. Bojana Visic, Jožef Stefan Institute, 
Slovenia and Weizmann Institute, Israel. The seminar will be held on 
Wednesday, November 1st 2017, at 13:00, in “Dr. Dragan Popović” library 
reading room of the Institute of Physics Belgrade.

Abstract of the talk:

Inorganic nanotubes (INT) and fullerene-like nanoparticles (IF) of MS2 
(M= W, Mo) were discovered some 25 years ago and are produced now on a 
commercial scale for various applications. A new environmentally 
friendly and scalable method to synthesize these nanostructures in 
ambient conditions, based on ultrashort pulse laser ablation, was 
reported.[1] The recent progress in the field, including various 
synthetic methods and properties such as mechanical, optical and 
electrical, has been recently summarized.[2]

In the past few years, layered two-dimensional semiconductors such as 
transition metal dichalcogenides (TMDs) moved into the focus of 
optoelectronics and nanophotonics research due to their exceptionally 
strong light – matter interaction combined with flexible processing and 
fabrication. Their optical spectra are dominated by strong excitonic 
resonances, in particular the A and B resonances associated with direct 
transitions between the two spin-orbit split maxima of the valence band 
(VB) and the conduction band (CB) minimum at the K point.

Most recently, it was shown that the extinction spectrum of WS2 NTs in 
aqueous dispersion is dominated by the strong coupling of the A and B 
excitonic resonances to a leaky-mode resonance (LMR) provided by the 
NTs’ high refractive index and cylindrical geometry.[3] We used 
femtosecond optical pump-probe spectroscopy to study the light-matter 
interaction in WS2 NTs in aqueous dispersion in the time domain.[4] The 
time-dependent non-equilibrium extinction spectra of photoexcited NTs 
was modeled with a phenomenological coupled oscillator (PCO) model, 
identifying relevant time-dependent parameters. We find that in this 
strong coupling regime, the time-dependent extinction spectra are 
governed by the electron dynamics in WS2, paving the way for a better 
understanding and device design for optoelectronic and photonic 
applications of TMD NTs.


[1]	K. Savva, B. Višić, R. Popovitz-Biro, E. Stratakis, and R. Tenne, 
ACS Omega 2, 2649 (2017).
[2]	B. Višić, L. S. Panchakarla, and R. Tenne, Journal of the American 
Chemical Society 139, 12865 (2017).
[3]	L. Yadgarov, B. Višić, T. Abir, R. R. Tenne, U. Arieli, A. Polyakov, 
R. Levi, T. V. Dolgova, V. V. Zubyuk,   A. A. Fedyanin, E. A. Goodilin, 
T. Ellenbogen, R. Tenne and D. Oron, under review.
[4]	B. Visic, L. Yadgarov, V. Vega-Mayoral, D. Vella, E. A. Pogna, S. 
dal Conte, R. Tenne, G. Cerullo, and C. Gadermaier, submitted.


Best regards,
Nenad Lazarevic

-- 
Institute of Physics Belgrade
Pregrevica 118, 11080 Belgrade, Serbia
http://www.ipb.ac.rs/