Séminaire DON : présenté par Prof. B. Dietzek – Ivansic

Prof. B. Dietzek – Ivansic, Inst. for Phys. Chemistry, Friedrich-Schiller-University Jena (Germany), Jena Center for Soft Matters

Abstract. Light is ubiquitous and light-driven processes are key, e.g., to the perception of the environment by vision, photosynthesis, to develop specific therapeutic approaches for cancer or to address the global challenge to transform our economy towards renewable energies. Consequently, research on light-activated molecules and materials, i.e., synthesis as well as functional and mechanistic studies on such systems are intensively researched. This talk will focus on two rather unexplored aspects to study light-driven molecular reactivity focusing on the excited-state dynamics in molecular intermediates in complex electron transfer cascades and photo-activated drugs for cancer therapy. I will discuss our experimental approaches, e.g., combining electrochemistry with ultrafast time-resolved spectroscopy, to investigate the light driven molecular reactivity from new viewpoints and highlight implications for photocatalysis and photodrug design obtained from the spectroscopic-mechanistic studies.

Séminaire IPCMS présenté par Andreas J. HEINRICH

Andreas J. HEINRICH

Center for Quantum Nanoscience, Institute for Basic Science (IBS)
Department of Physics, Ewha Womans University
Seoul, Republic of Korea

Résumé:

There is a strong international research effort in the area of quantum information science. Here, the concepts of quantum coherence, superposition and entanglement of quantum states are exploited. These concepts were originally shown with photons as well as atoms and ions in vacuum traps. Over the past two decades, many advances at studying such quantum coherence in solid-state and molecular architectures have evolved [1].
In this talk we will focus on quantum-coherent experiments in Scanning Tunneling Microscopy (STM). STM enables the study of surfaces with atomic-scale spatial resolution and offers the ability to study individual atoms and molecules on surfaces. Here at Ewha, we have one of the world’s best facilities for such studies. STM can also be used to move atoms with atomic-scale precision, which enables us to build engineered nanostructures where each atom is in the exactly correct place.
In order to study qubits with STM, we recently learned how to combine STM with electron spin resonance [2,3]. Spin resonance gives us the means to quantum-coherently control an individual atomic or molecular spin on a surface. Using short pulses of microwave radiation further enables us to perform qubit rotations and learn about the quantum coherence times of our spins [4]. Finally, we will finish with unpublished results on multi-qubit operations with spins on surfaces.
1. Andreas J. Heinrich, William D. Oliver, Lieven M. K. Vandersypen, Arzhang Ardavan, Roberta Sessoli, Daniel Loss, Ania Bleszynski Jayich, Joaquin Fernandez-Rossier, Arne Laucht, Andrea Morello, “Quantum-coherent nanoscience”, Nature Nanotechnology, 16, 1318-1329 (2021).
2. Susanne Baumann, William Paul, Taeyoung Choi, Christopher P. Lutz, Arzhang Ardavan, Andreas J.
Heinrich, “Electron Paramagnetic Resonance of Individual Atoms on a Surface”, Science 350, 417 (2015).
3. Yi Chen, Yujeong Bae, Andreas Heinrich, “Harnessing the Quantum Behavior of Spins on Surfaces”, Advanced Materials 2022, 2107534 (2022).
4. Kai Yang, William Paul, Soo-Hyon Phark, Philip Willke, Yujeong Bae, Taeyoung Choi, Taner Esat, Arzhang
Ardavan, Andreas J. Heinrich, and Christopher P. Lutz, “Coherent spin manipulation of individual atoms on a surface”, Science 366, 509 (2019).

Support from Institute for Basic Science (IBS-R027-D1) is gratefully acknowledged

Séminaire Axe 2 présenté par Fernanda de Avila Abreu

Fernanda de Avila Abreu (Microbiology Institute, Federal University of Rio de Janeiro (UFRJ)

Résumé :

Magnetotactic microorganisms are capable of synthesizing membrane-enclosed intracytoplasmic magnetic nanocrystals. The ability to produce these structures is shared among living beings that use the geomagnetic field as a form of guidance in migratory processes. Due to their structural simplicity concerning macroorganisms, magnetotactic bacteria have been widely studied regarding the synthesis of magnetic nanocrystals and magnetic orientation. The nanocrystals produced by magnetotactic bacteria have a narrow size range, consistent shape, chemical purity, crystallographic perfection, and stable properties. Furthermore, the synthesis process is considered entirely sustainable. Therefore, scaling up the production of these magnetic nanoparticles of biological origin, as well as innovative biotechnological approaches, are being studied towards a sustainable future.

Contact : Ovidiu ERSEN,  ovidiu.ersen@ipcms.unistra.fr  

Séminaire DCMI : Dr. Civan AVCI

Dr. Civan AVCI

Laboratoire de Chimie de la Matière Condensée de Paris
(UMR 7574 Sorbonne Université, CNRS, Collège de France)

Résumé : Zeolitic imidazolate framework-8 (ZIF-8) is a member of the metal-organic framework (MOF) family that is a new class of material with ultra-high porosity useful for several applications including gas storage, molecular sieving and catalysis. So far, countless studies have been reported, showing applications that are related to the bulk properties of MOFs, and by extension ZIF-8. On the other hand, the controlled manipulation of these molecular crystals at the nano-scale is still embryonic. Here, the presentation will focus on colloidal manipulation of ZIF-8 crystals: their size and shape engineering using top-down and bottom-up approaches at the nano-scale, their self-assembly into superstructures at the meso-scale and their potential applications (such as photonics) at the macro-scale.

à l’Auditorium de l’IPCMS et via Zoom
https://us02web.zoom.us/j/84304431750?pwd=bHJCdVl2NnZyZUFRV1lVaXpGNFAxZz09