Structuration of aqueous interfaces by Terahertz pulses: A study by Second Harmonic and Sum Frequency Generation

Project Information

SAInTHz

Grant agreement ID: 896908

DOI

10.3030/896908

Project closed

EC signature date 11 March 2020

Start date 1 September 2020

End date 31 May 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 196 707,84

EU contribution

€ 196 707,84

Coordinated by

UNIVERSITE DE BORDEAUX
France

Periodic Reporting for period 1 - SAInTHz (Structuration of aqueous interfaces by Terahertz pulses: A study by Second Harmonic and Sum Frequency Generation)

Reporting period: 2020-09-01 to 2022-08-31

Summary of the context and overall objectives of the project

Water interfaces are omnipresent in nature and technologies. They are of utmost importance to the understanding of diverse biological and chemical processes, ranging from protein folding to atmospheric chemistry or colloidal stability. They are also of paramount importance to the development of advanced catalysts and energy storage devices. For instance, ocean absorb about 30% of the carbon dioxide (CO2) that is contained in the atmosphere. As levels of atmospheric CO2 increase from human activity such as burning fossil fuels and changing land use, the amount of CO2 absorbed by the oceans also increases. When CO2 is absorbed by seawater, a series of chemical reactions occur resulting in an increased concentration of hydrogen ions. This process has implications for plants and animals living nearby, as well as for climate change modelling. In another context, electrochemical cells and systems play a key role in a wide range of industrial sectors. These devices are critical enabling technologies from an energetic point of view: renewable energy, energy production, management, conservation and storage. They are also important from an environmental point of view: pollution control, monitoring, and reduction of greenhouse gases. Since the electrochemical responses depend on the microscopic chemical composition of the liquid/solid interface itself, a better understanding of the microscopic structure and the dynamics at the fundamental level first, will have an impact for the applications and developments in terms of cost, life time and performance.
Charged water interfaces are ubiquitous. They are involved in many natural phenomena and are of great importance to the development of numerous natural processes and technologies ranging from protein folding to photocatalysis for water splitting and/or proton-exchange membrane fuel cells.
Even though significant progress has been made over the previous decades8-9 our understanding of the fundamental physical science at aqueous interfaces remains limited compared to that of the bulk, because the investigation of these interfaces with non-invasive probes is still a significant challenge.
Water interfaces are the most commonly used platforms for chemistry and biological processes, but the current understanding at the molecular level and ultrashort timescales is an uncharted territory.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The aim of this fellowship has been to design and develop a hybridized terahertz/optical setup to study aqueous interfaces. The main challenge realization of the project originates from highly technical requirements to be able to study very low signals for water interfaces. The project requires to implement several state of the art optical tools1–5, coupled to a state-of- the art terahertz pulse generation6,7. As a reminder, the main optical techniques used to study aqueous interfaces are sum frequency generation (SFG) and second harmonic generation (SHG).
As such, the main scientific, research objectives (RO) of SAInTHz were:
ROi. Studying the air/water interface by SHG/SFG with an applied electrostatic potential (electrochemical cell)
ROii. Studying the air/water interface with SHG/SFG and terahertz-induced charge.

At present, the technical parts of the project have been done, however, the application to aqueous interfaces remains to be achieved. As such, the project has achieved some of its objectives and milestones. However, corrective action was required.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The impact of the project is divided into two categories: scientific, and in terms of the career of the researcher. The project has had major impacts on the future career of the researcher.

Enhancing the future career prospects of the researcher after the fellowship
The main career goal of the PI, after completion of the fellowship, was ‘to apply for a permanent position in France ‘. Such positions are highly competitive, with a typical 3-4 % success rate for applicants per field of research every year. The position allows the researcher to focus on his/her research activities, with or without teaching duties depending on the position.

The PI had been applying to Junior researcher positions in CNRS, associate teacher positions and tenure track positions. She has been ranked two times (7 for 5 positions in 2020, 7 for 6 positions in 2023, still waiting for the admission results) for CNRS and was ranked first for Junior Chair position in 2022, a date concomitant with the fellowship. The Marie-Curie Sklodowska fellowship is a prestigious fellowship recognized throughout Europe, and the PI firmly believes that the MSCA fellowship strongly contributed to obtaining this position. The PI is now a full member of the Photonics and Matters team, and part of the PULS group. She is therefore collaborating with.E. Freysz (supervisor of the MSCA fellowship) on a daily basis, on the topic of THz and nonlinear optics and J. Degert (collaborator), both other members of the PULS group. Importantly, the MSCA fellowship allowed the PI to start her own research activity and group. Financial support of the MSCA allowed her to purchase necessary optomechanical components to build an optical setup from scratch, on a dedicated optical table.

As previously explained, the PI also answered several grant applications throughout the duration of SAInTHz. The next career step of the researcher is now to fully secure a Region Aquitaine grant (approx. 170 k€), in order to increase human resources for her group and warranty financial autonomy and support for the next 5 years. In addition to this, the PI aims at applying for the ‘Habilitation à diriger les recherches’, a necessary qualification in France to have the right to supervise PhD thesis and further apply to the position of Professor. As such, no particular innovation activities were launched during this fellowship. Thanks to positive and constructive reviews obtained from his ERC starting grant application, the PI is also willing to resubmit her application for an ERC consolidator grant during the next five years (eligibility period).

From a scientific point of view, this fellowship has also had its benefits. Indeed, it constituted for the PI a novel experience to work on Terahertz and discover some of the related challenges. The researcher was able to extend her skills in optics.

All these points show that this MSCA postdoctoral fellowship has certainly enhanced the career prospects of the researcher.

Impact on the European research and economy competitivity and dissemination
Due to its highly fundamental aspect, the project is not expected to enhance innovation capacity, strengthen competitiveness and growth of companies in the short term. It is neither expected to address issues related to climate change or industrial/societal needs at regional or bring benefits for society. The work does not contribute towards European policy objectives and strategies and has no impact on policy making.
The dissemination strategy detailed in the proposal was altered according to the circumstances. Indeed, with the international situation and the advancement of the project, publications and conference contributions were not as abundant as planned.

schematic representation of the project