LACUS Seminars

Dr. Philip Kurian (Howard University, Washington DC, USA)

Title : Ultrafast tryptophan-to-tryptophan energy transfer and superradiance in tubulin polymers.

Abstract: Oxidative stress from aerobic processes is a pathological hallmark of degenerative disorders such as Alzheimer’s disease and cancer. The precise role of reactive oxygen species (ROS) in the disease process, however, is poorly understood. It is known that the production of ROS by mitochondria can result in ultraweak photon emission (UPE) within cells, and UPEs in the UV and visible ranges have been observed with modern equipment during different stages of the mitotic cycle. Surrounding biomolecules can absorb these photons via aromatic amino acids (e.g., tryptophan and tyrosine), nucleobases (e.g., adenine, cytosine, guanine, thymine), and other chromophoric constituents, forming excited singlet or triplet transition states. One likely absorber is the microtubule cytoskeleton, as it forms a vast network spanning neurons, is highly co-localized with mitochondria, and shows a high density of aromatics, but DNA and the photoactive receptors in the mitochondrial membrane are also potential candidates. These networks may traffic ROS-generated endogenous photon energy for cellular signaling, or they may serve as dissipaters of such energy to protect the cell from potentially harmful effects. Recent modelling efforts based on ambient temperature experiment are presented, showing that such biopolymers can feasibly absorb and channel these photoexcitations via resonance energy transfer, on mesoscopic length scales of physiological significance. Additional simulations using a non-Hermitian Mukamel Hamiltonian demonstrate the possible existence of superradiant states in microtubules corresponding to similar observed phenomena in cylindrical chlorophyll complexes.

Thursday 5 July 2018 / 16:00 / CH G1 495

Dr. Jianbo Hu (California Institute of Technology and China Academy of Engineering Physics)

 

Title : 4D visualization of ultrafast lattice deformation in solids under laser excitation.

 

Abstract: The high scattering cross-section for electron/matter interaction, the atomic-scale spatial resolution, and the ultrafast temporal resolution of ultrafast electron diffraction (UED) represent the key elements that make this technique a unique tool for the dynamic investigation of nanomaterials. Here I introduce the general concept of UED, and then present a few applications on investigating the laser-induced lattice deformation in solids, including transient structures of phase change materials, energy localization in quantum dots, and rippling dynamics of free-standing graphene.

Monday 25 June 2018 / 11:00 / CH G1 495

Mrs. Selene Mor (Fritz Haber Institute, Berlin, Germany)

Title : Ultrafast electronic band gap control and inhibition of the photoinduced structural phase transition in an excitonic insultaor

Friday 15 June 2018 / 11:00 / CH G1 495

 

Dr. Wojciech Gawelda (European XFEL, Germany)

Title : Scientific opportunities and challenges for femtochemistry using X-ray Free Electron Lasers

Friday 04 May 2018 / 11:00 / CH G1 495

 

Mr. Paolo Usai (Università degli studi di Cagliari)

Title : Characterization of 2D perovskites via time-resolved ultrafast spectroscopy techniques

Thursday 3 May 2018 / 15:00 / CH G1 495

 

Dr. Jeremy Rouxel (University of California)

Title : Time-resolved nonlinear signals for X-ray spectroscopy and diffraction

Thursday 8 March 2018 / 14:00 / Room CH G1 495
 

Dr. Marino Marsi (Université Paris-Saclay France)

Title : Ultrafast study of out-of-equilibrium quantum materials

Tuesday 20 February 2018 / 11:00 / Room CH G1 495

 

LACUS Day 2018

Wednesday 14 February / Room CE11

 

Prof. Richard Friend (Université of Cambridge)

Title : Molecular semiconductors for LEDs and solar cells: designing around the Coulomb interaction

Monday 20 November 2017 / 16:30 / Room BCH 2201

 

Dr. Fulvio Parmigiani (University of Trieste and University of Cologne)

Title : A Non-equilibrium approach to the optical spectroscopy of high-temperature superconductors

Wednesday 8 November 2017 / 10:00 / Room CH G1 495
 

Prof. Nikolaus Ernsting (Humboldt-Universität Berlin)

Title : Hydration Dynamics Seen from the Inside: Possibilities of a Molecular THz Spectrometer

Thursday 2 November 2017 / 10:30 / Room CH G1 495

 

Prof. Laura Herz (University of Oxford)

Title : Mechanisms limiting charge-carrier recombination and mobilities in metal halide perovskites

Thursday 29 June 2017 / 16:30 / BCH 2201

 

Prof. Omar Mohammed (KAUST)

Title : Mapping Carrier Dynamics on Semiconductor Material Surfaces and at Interfaces using Laser Spectroscopy and 4D Electron Microscopy

Thursday 22 June 2017 / 16:30 / BCH 2201