New spectroscopy method facilitates studies of ultrafast energy transfer in a molecule and between molecules

The measuring system

Studies by Prof. Czesław Radzewicz from Optics Division of the Faculty of Physics University of Warsaw in cooperation with scientists from Institute of Physical Chemistry Polish Academy of Sciences resulted in an invention of a new ultrafast optical spectroscopy method (femtosecond infrared pump – stimulated Raman probe spectroscopy, fs-IR-SRS).

The method enables studies on how thermal (‘vibrational’) energy delivered to a specific chemical group, spreads over other chemical groups in the same molecule and also over neighboring molecules. The method determines the time of such ‘energy transfer’ down to hundreds of femtoseconds (~10^‑13 s). Importantly, the methods used up to now enabled simultaneous observation of energy transfer into, at most, a few chemical groups. The method developed by Radzewicz’s group facilitates ‘watching’ energy transfers to all chemical group in a sample in a single experiment. It supplies much more information then conventional methods and thus acquiring the data last much shorter.

Graphics from the cover of the journal

The researchers used the new method to study transfer of thermal/vibrational energy in liquid water. In liquid water the molecules are interconnected with a dense network of hydrogen bonds and vibrational energy spreads very quickly. The new method enables much more precise description of this important physico-chemical process.

The unique advantages make a new method a perfect tool to resolve urgent problems in the fields of physical chemistry and biochemistry. It should make possible i.e. characterization of intermolecular interactions in liquid phase, resolving secondary structures of hydrated proteins and peptides and also understanding mechanisms of enzyme-catalyzed reactions.

The publication on the new technique is advertised on a cover of recent Physical Chemistry Chemical Physics journal.

Publication:
M. Pastorczak, M. Nejbauer, Cz. Radzewicz, "Femtosecond infrared pump–stimulated Raman probe spectroscopy: the first application of the method to studies of vibrational relaxation pathways in the liquid HDO/D₂O system" Physical Chemistry Chemical Physics 2019, 21, 16895).
https://pubs.rsc.org/en/content/articlepdf/2019/cp/c9cp00855a.

Funding:
Project was funded by Polish National Science Center (NCN) - Opus grant No. UMO-2015/17/B/ST4/04035.