Upcoming LACUS seminars
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.
The event is sponsored by Swissphotonics
Roberto Monni, Gloria Capano, Gerald Auböck, Harry B. Gray, Antonín Vlcek, Ivano Tavernelli, Majed Chergui.
“Vibrational coherence transfer in the ultrafast intersystem crossing of a di-platinum complex in solution.”
PNAS 25 June 2018. DOI: 10.1073/pnas.1719899115
Simon P. Neville, Majed Chergui, Albert Stolow, Michael S. Schuurman. “Ultrafast X-ray spectroscopy of conical intersections”
Physical Review Letters 120, 12 June 2018.
- Edoardo Baldini’s (LSU) Ph.D thesis “Nonequilibrium Dynamics of Collective Excitations in Quantum Materials” is now available.
- The LACUS activity report for the first two years 2016-2017 is now available.
- Majed Chergui (LSU) wins the Khwarizmi International Award 2018.
- Latest hot results in the news (LAPD): 3D printing directly inside the body made possible by this Swiss needle.
- LND’s ultrafast TEM with a Field Emission Gun is now fully operational.
- Raffaella Buonsanti (LNCE) got an ERC starting grant.
- Arianna Maciaro (LBP) got an Ambizione Fellowship, SNSF: Understanding Photoinduced Processes at Semiconductor/Aqueous Interfaces by Surface-Specific Spectroscopic Techniques.
- Raffaella Buonsanti (LNCE) got a SNSF Assistant Professor Energy grant
- Highlight article (LNCE): New method improves stability of perovskite quantum dots
- A new second harmonic microscope capable of 3D imaging of interfacial water and water in pores (LBP).
- Ulrich Lorez (LND) got an ERC starting grant.
- The 24th issue of the Laserlab Newsletter “LASERLAB Forum” is published featuring an article by Edoardo Baldini and Majed Chergui (LSU) on the absorption of light by titanium dioxide.
- Majed Chergui (LSU) is the keynote speaker of the 78th “Sir Jesse Boot Lecture” at the University of Nottingham, where he will talk about “Ultrafast Chemical Dynamics in Solution: Optical and X-ray studies”.
- LACUS seminar by Prof. Richard Friend (University of Cambridge – UK):
“Molecular semiconductors for LEDs and solar cells: designing around the Coulomb interaction”
- New article of the LO group by D. Conkey et al. in Optics Express.:High power, ultrashort pulse control through a multi-core fiber for ablation:
An ultrashort laser ablation fiber probe shows great potential for microstruring application. Lensless focusing and digital scanning of the focus spot, using wavefront shaping techniques, lead to a submillimeter femtosecond laser ablation tool.
Ultrashort pulse ablated samples of thin gold film deposited on glass (a. EPFL letters and b. the Matterhorn).
- Inaugural Visionary Lecture by M. Chergui at the OSA Frontiers in Optics and Laser Science meeting (Washington DC, September 2017)
- New article of the LUMES group by J. Müller et al. in Phys. Rev. Lett.:Magnetic Skyrmions and Skyrmion Clusters in the Helical Phase of Cu2OSeO3:
Skyrmions are nanometric spin whirls that can be stabilized in magnets lacking inversion symmetry. The properties of isolated Skyrmions embedded in a ferromagnetic background have been intensively studied. We show that single Skyrmions and clusters of Skyrmions can also form in the helical phase and investigate theoretically their energetics and dynamics. The helical background provides natural one-dimensional channels along which a Skyrmion can move rapidly. In contrast to Skyrmions in ferromagnets, the Skyrmion-Skyrmion interaction has a strong attractive component and thus Skyrmions tend to form clusters with characteristic shapes. These clusters are directly observed in transmission electron microscopy measurements in thin films of Cu2OSeO3. Topological quantization, high mobility, and the confinement of Skyrmions in channels provided by the helical background may be useful for future spintronics devices.
Individual skyrmions and skyrmions clusters in the helical phase of Cu2OSeO3.
Edoardo Baldini, Tania Palmieri, Thomas Rossi, Malte Oppermann, Enrico Pomarico, Gerald Auböck, and Majed Chergui
“Interfacial Electron Injection Probed by a Substrate-Specific Excitonic Signature.”
- New article of the LUMES group by E. Baldini et al. in Phys. Rev. Lett.:
Illustration of the ultrafast dynamics of MgB2. After the interaction with the solid, the ultrashort laser pulse leads to the excitation of both sigma and π carriers. The nonthermal sigma carriers are strongly coupled to the branch of the E2g phonon mode and efficiently generate hot phonons during the first 170 fs. Subsequently, the energy stored in the hot phonon subsystem is released to the π carriers via interband scattering and to low-energy phonons via anharmonic decay.The microscopic details of the interplay between the two subsystems in multi band superconductors were lacking to date and represent an important information for the manipulation of superconductivity in these type of materials.
- This month’s issue of CHIMIA is entirely dedicated to LACUS and features a collection of articles presenting the capabilities of this facility by several LACUS groups (Chimia 5/2017, Vol. 71).
- Editorial by Prof. Majed Chergui
- Harmonium: An Ultrafast Vacuum Ultraviolet Facility by C. Arrell et al. (LSU and LSE)
- Time-resolved ARPES at LACUS by A. Crepaldi et al. (LSE and LSU)
- Aqueous Nanoscale Systems by S. Roke (LBP)
- Semiclassical Approaches Time-resolved Spectroscopy by J. Vanicek (LCPT)
- LOUVRE: Ultrafast Ultraviolet Spectroscopies by M. Oppermann et al. (LSU)
- Ultrafast Lasers to Tailor Material by Y. Bellouard (GALATEA)
- Prof. Luc Thévenaz is coordinator of the Horizon 2020 Marie Curie Innovative Training Network “FINESSE”.
Fundamental and practical challenges facing our society can be addressed with new methods and thus approached from a new perspective. Examples of present day challenges are energy conversion, information technology, new materials and biology and medicine.
Over the last decade, ultrafast science and technology have made enormous progress, opening a large variety of new research fields and applications. Examples include table-top high-harmonic generation that allow new forms of spectroscopy and diffraction, lab-based sources of ultrashort electron pulses and sources of terahertz radiation that opened new directions in materials science, chemistry and biology and new sources of ultrashort X-ray pulses, such as X-ray free electron lasers.
The Lausanne Centre for Ultrafast Science (LACUS) brings together the EPFL teams working in Ultrafast Science and Technology with experimental and theoretical methods as well as those using ultrafast technology in different applications. Research areas are very diverse, spanning from fundamental to applied research and they present a very high degree of complementarity. Several EPFL groups are pioneers in ultrafast science and technology and LACUS pools in the expertise in the development and the use of advanced ultrafast laser technology, X-ray and electron technology and associated methods, along with the EPFL theory groups. It also aims at complementing and strengthening existing Swiss scientific infrastructures, e.g. the Swiss Light Source and the SwissFEL.