seminars

NEW TOOLS FOR CHEMISTRY: APPLICATIONS OF THE HIGH –ORDER HARMONIC GENERATION FOR THE STUDIES OF THE ULTRAFAST DYNAMICS OF BIOLOGICAL MOLECULES

Physical and Analytical Chemistry Seminar

Lecturer: Dr. Raluca Cireasa

Date:
02-02 Jun 2019 @ 12:30

Location: Faculty Seminar Room

Abstract:

The high harmonic generation (HHG) has emerged as a new light source and has put forward new spectroscopic techniques providing structural and dynamical information with unparalleled temporal resolution. I will present two examples in which we took advantage of the unique capabilities of HHG to investigate molecular properties and dynamics of more complex systems of interest for chemistry and biology. We have employed HH radiation to study the fragmentation and dynamics of radiosensitisers (5-Halouracils), i.e. molecules that enhance the effect of radiotherapies and of Glycine. The spectral and temporal characteristics of the XUV radiation enabled us to measure the ultrafast dynamics (10 -100 fs) underlying the photo-stability and the photo-damage processes occurring upon excitation in the valence region. In particular, ultrafast proton migration dynamics was associated with damage induced through tautomerisation and/or isomerisation processes.[1,2]

Another application of HHG concerns its use as a new spectroscopic tool enabling to investigate chirality on as and fs timescales. We found out that the slight disparity of the laser-driven electron dynamics induced in the two enantiomers of Fenchone was recorded in their harmonic spectra as large elliptical dichroism of opposite sign. The laser ellipticity that maximises the yield of each HH reflects with 100 as resolution a sub-cycle chiral dynamics.[3]

 

  1. P. Çarçabal et al., Faraday Discuss. 194, 407 (2016)
  2. M.C. Castrovilli et al. J. Phys. Chem. Lett. 9, 6012, (2018)
  3. R. Cireasa et al., Nat. Phys. 11, 654 (2015)