Bottom-up design of materials using organic building blocks

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Prof. Jennifer MacLeod
Queensland University of Technology

Abstract: One of the goals of nanoscience is achieving precise control over the structure and function of nanoscale architectures at surfaces. Bottom-up approaches using molecular building blocks present a flexible and intuitive approach to this challenge. Combining the Lego-like modularity of molecules with the epitaxial and reactive influences of surfaces creates a range of opportunities to build exciting new nanoarchitectures, which potentially have interesting and/or useful electronic properties.

I will describe two approaches to the fabrication of 1D and 2D organic materials. The first approach is based on self-assembly, which is spontaneous organisation of building blocks via non-covalent interactions. Self-assembled films can be highly-ordered and relevant to, e.g., thin-film organic semiconducting devices. The second approach addresses this point. The second approach involves covalently bonding organic building blocks on a surface, which can create robust materials with tailored electronic properties, I will discuss our recent work in studying the reactions of halogenated and carboxylated molecules at metal surfaces, where we have been focussing on understanding the effect of heteroatoms in the coupling reaction and the subsequent formation of oligomeric and polymeric structures. These studies draw on a combination of scanning tunnelling microscopy, photoelectron spectroscopy and near-edge x-ray absorption fine structure to gain a well-rounded insight into the processes.

The end goal of this work is to establish an understanding of how structure and function are related in these materials. Measuring the electronic properties of organic materials can be challenging, as not many methods offer a way to directly characterise their unoccupied electronic structure. I will provide an overview in our recent work in developing an inverse photoelectron spectrometer optimised for use on organic materials. This instrument, in combination with ultraviolet photoelectron spectrometry, allows us to measure all relevant energy levels in our organic materials.

Superfluids of light

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Prof. David Snoke
University of Pittsburgh, USA

Abstract: It is possible to engineer the properties of photons in an optical medium to have an effective mass and repulsive interactions, so that they act like a gas of atoms. These “renormalized photons” are called polaritons. In the past decade, several experiments have demonstrated many of the canonical effects of Bose-Einstein condensation and superfluidity of polaritons. In this talk I will review some of this past work and present recent results with polaritons that have very long lifetime, including movies of equilibration and damped oscillations of a condensate.

Exploring the Precision Frontier with Belle II

 

Prof. Markus Prim
Karlsruhe Institute of Technology
& KEK (High energy accelerator Research organization, Tsukuba, Japan)
This colloquium will be held at 11 am, 14th February 2020, in  Parnell building(07), Room #222
Abstract:
The Belle II experiment is a next-generation B-Factory located at the SuperKEKB electron-positron collider facility in Tsukuba, Japan. The experiment started to record collisions in 2018 and aims to collect a data sample of 50/ab in the coming years. The large anticipated collision data set will allow for precision tests to challenge the Standard Model of particle physics and search for signs of new physics processes and phenomena beyond the direct production threshold of the Large Hadron Collider. This talk will present the current status of Belle II and discuss the ongoing effort to search for signs of new physics at the precision frontier.

Challenges in particle physics and cosmology

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Prof. Ignatios Antoniadis
LPTHE, CNRS, Paris, France &
Albert Einstein Center, ITP,
University of Bern, Switzerland
This colloquium will be held at 11 am, 30th December, in  Parnell building(07), Room #222
Abstract:
Particle physics studies the elementary constituents of matter and their fundamental forces. Very short distances are explored by particle collisions at very high energies, creating conditions similar to those governing the Universe just after the Big Bang. This is the reason that the same physics is also explored by cosmology through observations on the sky at very large distances.

The current theory of particle physics, called Standard Model, provides an accurate description of all known physical phenomena in the microcosmos and its last ingredient, needed to explain the origin of mass of elementary particles, was discovered at the Large Hadron Collider (LHC) at CERN in 2012. On the other hand, the Standard Model of cosmology describes very well observations, confirmed recently by the Planck satellite experiments, pointing to the existence of a new dark sector of the Universe containing dark matter and dark energy.

Particle physics and Cosmology are now entering into a new era of unexplored territories beyond the current standard models with new challenges and open questions to answer. A global effort is ongoing both in theory and in experiment, promising new discoveries towards unveiling the fundamental laws of Nature.