M. Juodėnas “Suspended and arranged Ag nanoparticles: self-assembly and resonances in nanophotonics” doctoral dissertation defence

Thesis Defense

Author, Institution: Mindaugas Juodėnas, Kaunas University of Technology

Science area, field of science: Technological Sciences, Materials Engineering, T008

Scientific Supervisor: Prof. Habil. Dr. Sigitas Tamulevičius (Kaunas University of Technology, Technological Sciences, Materials Engineering, T008)

Dissertation Defence Board of Materials Engineering Scientific Field:
Prof. Habil. Dr. Arvaidas Galdikas – chairman (Kaunas University of Technology, Technological Sciences, Materials Engineering, T008)
Dr. Mindaugas Andrulevičius (Kaunas University of Technology, Technological Sciences, Materials Engineering, T008)
Prof. Habil. Dr. Vidmantas Gulbinas (Center for Physical Sciences and Technology, Natural Sciences, Chemistry, N003)
Prof. Habil. Dr. Yogendra Kumar Mishra (Southern Denmark University, Technological Sciences, Materials Engineering, T008)
Prof. Habil. Dr. Arūnas Ramanavičius (Vilnius University, Natural Sciences, Physics, N002)

The dissertation defence takes place online.

The doctoral dissertation is available on the internet and at the library of Kaunas University of Technology (K. Donelaičio g. 20, Kaunas).

Annotation:

This dissertation describes phenomena related to light-nanoparticle interaction. Experimental results and models reveal new knowledge about processes taking place at a picosecond time scale (1 / 1‘000‘000‘000‘000 of a second) and at a length scale 1’000 times shorter than the width of a human hair. The described findings will pave the way for novel, light-manipulating devices with ultrafast functions.
Metal nanoparticles can resonate with light. If they were arranged in periodic arrays, resonantly scattered light could interact with diffracted light travelling in the plane of the array. This interaction features strong electric fields and extremely narrow extinction peaks – both very useful in nanophotonics. This phenomenon is demonstrated by employing a unique periodic nanostructure generation method—particle self-assembly—which makes the nanoparticles themselves assemble into predefined positions on a patterned substrate.
After the nanoparticle resonance, the relaxing electrons transfer their energy to the lattice of the metal. For this reason, metal nanoparticles expand and excite mechanical oscillations—changes in nanoparticle shape and size. Since the color of nanomaterials usually depends on these parameters, the oscillations can be observed using a transient absorbance measurement. This dissertation discusses the influence of optomechanical oscillations on both suspended and arranged nanoparticle resonances. Revealed discoveries illustrate the interactions taking place at an ultrafast time scale and photonic length scale which promise a new generation of nanophotonic elements.

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