糖心TV

Speaker: Professor Steve Leone

Title: An X-Ray Spectroscopic Revolution in Time-Resolved Molecular and Solid-State Dynamics

Location: MAS 2.05-06

Date and Time: Tuesday July 19^th at 2:00-3:00 pm followed a drinks/snacks reception

Abstract

Intriguing physics and chemistry problems abound in the pursuit of attosecond science, as such measurements push the boundaries of fundamental electron dynamics timescales. The x-ray transitions accessed by attosecond pulses are responsive to charge, chemical oxidation state, and electronic environment. An introduction to attosecond measurements is presented, with the goal to reveal electron dynamical timescales. Investigations involve explorations of transient states in photodissociation, coherent electronic superpositions and charge migration in molecules, and determination of carrier dynamics in semiconductor band gap materials.

Brief Bio of Steve Leone

Steve is one of the fathers of utilizing lasers to study gas-phase reactions and energy-transfer processes, including trail-blazing applications of laser initiated chemistry as well as infrared chemiluminescence detection. To put this into perspective, entire conferences are now dedicated to these areas that Steve was instrumental in developing. His work on photodissociation quantum yields and energy transfer has been paramount to our understanding of the fundamental processes occurring at the molecular level during the making and breaking of chemical bonds. Steve also pioneered the application of soft x-ray pump-probe spectroscopy whereby high-energy photons can be used to study energy transfer processes in molecules that occur on a millionth of a billionth of a second. Steve’s demonstration of how photon energy is absorbed by molecular bromine and partitioned into the spin-orbit coupled states of the dissociating bromine atoms is a textbook example of the importance of soft x-rays as a probe, paving the way for 100s of future studies on energy transfer processes in more complex polyatomic systems. Steve’s creativity and insatiable curiosity is complemented by his tremendous physical insight. Having recognised the importance of using soft x-rays as probes of chemical reactivity, he took the bold step to extend the time-resolution of these measurements. At Berkeley, he has recently developed multimillion-dollar world-leading capabilities in attosecond physics, in which his group is now able to probe motion of electrons (10s of a billionth of a billionth of second). He has applied these cutting-edge experimental techniques to study electron motion in krypton, providing another textbook example of how these incredibly short pulses of light can help understand processes at the quantum level. Most recently, he has extended this approach to study how electrons move through silicon, essentially unravelling the speed limit in electronic circuitry.

In addition to his leadership in the scientific community, Steve is second to none when it comes to his generosity to help others progress in their careers. Steve has had countless PhD students (60) and postdocs (200) emerge from his group; Steve has guided each and every one of them, with 70 of these scientist now holding faculty positions in universities across the world (in the UK alone, there are 5 that are full professors). Helping young scientists reach their goals is a hallmark of Steve’s character.