In-situ Imaging of Laser-Matter Interactions at Nanoscale

by Ms Tugba Isik

Wednesday 9 Feb 2022, 14:00 → 15:00 US/Pacific

Speaker: Tugba Isik

Tugba Isik is a Ph.D. candidate in the School of Mechanical Engineering at Purdue University and works as a visiting researcher at University of Connecticut. She holds an MS in Mechanical Engineering from Purdue University and has received her BS in Mechanical Engineering from Istanbul Technical University in Turkey. Her current research focuses on investigation of laser-induced dynamic events in  nanomaterials in real-time via in-situ TEM. She aims to combine various microscopy techniques, such as novel ultrafast transmission electron microscopy (UTEM), aberration corrected S/TEM, and the dual SEM/FIB systems with finite element analysis to develop a better understanding of laser-matter interactions at nanoscale. Her work has been so far published in JACS, Journal of Applied Physics, Materials & Design, Nanoscale, Propellants, Explosives, Pyrotechnics (PEP), and Soft Matter and presented at Microscopy and Microanalysis (M&M).

Title: In-situ Imaging of Laser-Matter Interactions at Nanoscale

Abstract:

The joining process of noble metal nanostructures have been often studied via simulations so as to develop better methodologies to achieve these structures. The main driving force for such research has been the use of these nanostructures in catalysis, biological applications, nanoelectronic devices and nanoelectromechanical systems for printed electronics. Tuning of relative proportions of the metallic components provides an effective way to tune optical properties. Compositionally modulated bimetallic nanowires show enormous potential in future electronic devices as spin valves, diodes and optical labels. The control over the composition and segment dimensions along the nanowires could be an effective way to incorporate optical contrast, electrical functionality and/or desired surface chemistry. Obtaining low resistance metal nanowire junctions by welding, while maintaining high optical transparency of the substrate has been the primary goal in designing transparent conductors with metallic nanowire meshes. The high resistance of the nanoparticle junctions mainly arises due to the presence of surfactant layers. Removal of these layers can lead to spontaneous welding of nanomaterials even at room temperature. 

Laser induced welding stands out from more traditional methods like wet chemistry or radiolysis as a rapid, easy and scalable fabrication route in synthesis of these structures. It has been also shown that employing pulsed lasers for synthesis and processing of nanomaterials offers enhanced control over the welding process. However, previous studies on laser assisted processing of nanomaterials have been ex-situ. Hence, the understanding of the welding dynamics at the nanoscale is so far limited due to lack of visualization techniques. As such, in-situ transmission electron microscopy (TEM) techniques are invaluable for real-time monitoring of morphology and composition change in these systems at the nanoscale and can provide insights to the step-by-step dynamics of the merging and alloying process.

This presentation will discuss the effect of pulsed laser heating on noble metal plasmonic nanostructures based on the results obtained from in-situ experiments conducted using the sample excitation laser of the ultrafast transmission electron microscope (UTEM). Heat transfer and electric field calculations will be shared to support the experimental findings.