OSC Colloquium: Mohammed Hassan

    Thursday, October 18, 2018 - 3:30pm - 5:00pm
    Meinel 307

    1630 E. University Blvd.

    3rd Floor Lobby area

    Host: Jason Jones


    Open to campus and public.


    Speaker: Mohammed Hassan 

    Topic: Attosecond Electron Imaging 

    Visit our website for future lecture dates and speaker information: http://www.optics.arizona.edu/news-events/events/colloquium For a list of our archived lectures: http://www.optics.arizona.edu/news-events/events/colloquium/archive


    In the last decades, the developments in attosecond (attosecond =10-18second) physics enabled the real-time studies of electron dynamics in matter. Tracing the electron motion in its native time scale becomes crucial for the accurate clocking of microscopic phenomena. The attosecond physics field was based on the generation and exploiting the extreme-ultraviolet (XUV) attosecond pulses for probing the electron dynamics in atoms, molecule, and nanostructure (1). Attosecond spectroscopy provides insights of the atomic and electronic motion in real-time. However, the trajectory of this motion in spatial domain, as the time evolves, remains beyond the reach. Therefore, the ultrafast field called for a new technique to map the atomic and electron motion in both time and space domains. Recently, the development of Ultrafast Electron Microscopy (UEM) and Diffraction (UED) permitted the imaging of atomic motion in real time and space. The temporal resolution in ultrafast electron imaging measurements, typically on the order of a few hundred femtoseconds, is limited by the electron pulse duration and its synchronization with the optical trigger pulse. Ultrafast electron imaging has found a vast range of applications spans chemistry, physics, material science, and biology (3).

    In this talk, I will discuss the synthesis of the world first optical attosecond pulses in the visible and nearby ranges and using this tool to control bound electron motion in atoms (2).  In addition, I will introduce the ultrafast imaging techniques and how we break the temporal resolution limits in UEM by generating a 30-fs electron pulse exploiting the optical gating approach (4). The obtainingof this few tens femtosecond temporal resolution in UEM opens the door- for the first time- to image the electron dynamics in real time. Finally, I will explain the generation of single-isolated attosecond electron pulses by optical gating to establish the attosecond electron imaging tool which we so-called "Attomicroscopy". Attomicroscopy will enable the imaging of the electron motion, last few hundreds of attosecond to few femtoseconds, in action (5).


    1. Corkum PB & Krausz F (2007) Attosecond science. Nat Phys 3 (6):381-387.
    2.  Hassan MT, et al. (2016) Optical attosecond pulses and tracking the nonlinear response of bound electrons. Nature 530 (7588):66-70.
    3. Ahmed H. Zewail Four-Dimensional Electron Microscopy Science 328 (5975), 187-193.
    4. M. Th. Hassan, J. S. Baskin, B. Laio, and A. H. Zewail, High-temporal-resolution electron microscopy for imaging ultrafast electron dynamics, Nature Photonics 11, 425–430 (2017).
    5. M. T. Hassan, Attomicroscopy: from femtosecond to attosecond electron microscopy. J. Phys. B: At. Mol. Opt. Phys. 51, 032005 (2018). 
    Speaker Bio(s): 

    Mohammed Hassan is an Assistant Professor of physics and optical science at The University of Arizona (UA). He is also a faculty member at the UA BIO5 Institute for Biomedical Science & Biotechnology. He earned his Ph.D. from Max-Planck Institute for Quantum Optics, Munich, Germany. Then, he joined Zewail’s group Caltech as a postdoc scholar. His expertise is in the attosecond physics and ultrafast electron microscopy fields. Dr. Hassan developed the light field synthesizer apparatus to generate the first optical attosecond pulse, the shortest light pulse documented in the Guinness World Records. Exploiting this tool, he was able to measure the time an electron takes to response to external light field. Also, he demonstrated the shortest, to date, electron pulse in an electron microscope. These breakthroughs have been published in high profile journals (Nature, Science, Nature Photonics, and PNAS). Hassan received the Gordon and Betty Moore Foundation research investigator award, the Air Force's Young Investigator award (YIP 2019), and the international Max-Planck fellowship. He has served as a reviewer for journals such as Nature Photonics, Nature communications, Optics Express, Optics letter, Optica, Journal of the Optical Society of America A, and the Journal of Nanophotonics. He has reviewed for NSF Proposal Review panels (AMO program). He is a member of multiple professional societies: American Physical Society (APS), Optical Society of America (OSA), American Association for the Advancement of Science (AAAS), international society for optics and photonics technology (SPIE), and American Association for Physics Teachers (AAPT). He is an executive member in Ultrafast Optical Phenomena (OU) technical group at OSA. He represented the OSA and National Photonics Initiative (NPI) at Congressional Visits Day (CVD), Washington, DC to advocate for science.


    Refreshments 3:30pm

    Lecture @ 3:45pm - 5pm