Prof. Gopal Dixit

Department of Physics, IIT Bombay, Mumbai India

E-mail: gdixit[at]phy.iitb.ac.in

 

Brief Bio-sketch:

After finishing Ph. D. in theoretical physics from IIT Kharagpur in 2011, I did my post-doc in Hamburg Germany, where I was involved in developing the theory and applications of time-resolved x-ray scattering. In mid-2013, I moved to Max-Born Institute Berlin Germany, where I was doing attosecond and strong-field physics. In December 2015, I joined IIT Bombay. I have received DAAD, Marie-Curie, Ramanujan and Max-Planck India visiting fellowships. My current research includes Time-resolved X-ray Scattering, Ultrafast Spectroscopy, 'Time-Delay' in Photoionization, High-Harmonic Generation, Characterization of Attosecond Pulses, Above-Threshold Ionization, Multiphoton Processes, Ultrashort Twisted Pulses, Ultrafast Chemical Reactions, Quantum Chemistry.

AN ERA OF ULTRAFAST SCIENCE: CATCHING ELECTRONS

With the tremendous technological advancement in recent years, it becomes possible to generate ultra-short and ultra-intense laser pulses. It is natural to envision imaging the electronic motion during physical, chemical and biological processes using these pulses. In this talk, I will discuss the pros and cons towards the goal of probing the electronic motion on ultrafast timescale. Few examples will be presented in this direction. In the case of coherent electronic motion, it is tempting to assume that the time-resolved x- ray scattering pattern is related to the instantaneous electron density of the sample. I will show that, in general, this expectation is not only quantitatively, but also qualitatively incorrect and will propose a possible way to image the instantaneous electron density via ultrafast x-ray phase contrast imaging. Furthermore, I will address following challenges: Does the time-resolved scattering patterns distinguish between different reaction paths in chemical reactions by direct imaging of the associated transient structures? And is the scattering patterns are sensitive to the valence electron rearrangement in chemical processes? I will demonstrate our proposed approach provides direct experimental access to the long-standing problem of synchronous versus asynchronous bond making and bond breaking in pericyclic reactions, which have been solely investigated, theoretically till date.