Chemistry and structure of aminogen radicals using chirped-pulse Fourier transform (sub)millimeter rotational spectroscopy

Informations projet

CP-FTmmW Aminogen

N° de convention de subvention: 894508

DOI

10.3030/894508

Projet clôturé

Date de signature de la CE 11 Mars 2020

Date de début 1 Septembre 2020

Date de fin 31 Août 2022

Financé au titre de

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Coût total

€ 196 707,84

Contribution de l’UE

€ 196 707,84

Coordonné par

UNIVERSITE DE LILLE
France

Periodic Reporting for period 1 - CP-FTmmW Aminogen (Chemistry and structure of aminogen radicals using chirped-pulse Fourier transform (sub)millimeter rotational spectroscopy)

Période du rapport: 2020-09-01 au 2022-08-31

Résumé du contexte et des objectifs généraux du projet

The principle objectives of my fellowship project are to measure and analyze the millimeter-wave rotational spectra of aminogen radicals CH2NH2 and CH3NH, which are potential reaction intermediates in the N chemistry in the interstellar medium leading to the synthesis of pre-biotic amino acids. Then the following experiment aim to investigate the reaction channels of these radicals with OH radical. To conduct these experiments, I need to develop an apparatus combining the chirped pulsed spectrometer, already developed in Lille before the start of the project, and the supersonic expansion technique coupled with direct current discharge. The expected results are the following: (a) spectral data, spectral model and line catalog of CH2NH2 and CH3NH; (b) understanding of reaction products between these radicals and the OH radical; (c) understanding of reaction channels between these radicals and the OH radical, i.e. the yield of each kind of reaction product, if the reaction leads to multiple different products.
The Covid-19 pandemic and then the subsequent ending of the transition period of Brexit in the winter of 2020 have posed significant influence on the project progress, delaying the main research task by 1 year. The delay made me unable to complete the planned research tasks and I had to seek deviation of the plan. For the planned research, I have accomplished to ~40% of the plan, which is at the stage before D1.3 in WP1. For the deviations, I chose to develop a general spectral treatment function that can help improving the signal to noise ratio of the chirped pulse data, and to study the spectra of formaldoxime (CH2NOH), nitrosomethane (CH3NO), and the 3-carbon imine 2-propanimine ((CH3)2CNH), which might be reaction products of the aminogen radical with OH, and which did not have precise millimeter-wave spectra available. These molecules themselves are also of astrochemistry interest and can be searched in the interstellar medium. By doing so, I have expanded the known molecular line catalogs, which will be beneficial for the identification of reaction products when this stage of experiment will finally be conducted in the future.
The main scientific achievements of this project so far are the following: (1) the development of a general spectral treatment function that improves signal to noise ratio of chirped pulse spectra; (2) the first laboratory measurement and analysis of 3 important isomers of N-bearing astrophysical molecules, CH2NOH, CH3NO, and (CH3)2CNH (Figures 1 and 2), in the millimeter-wave range; (3) the implementation of the instrument and software and reproduction of radical species CH2CN (Figure 3) and CH3CO.
The results of the project, mainly from the deviations I chose to compensate the extreme delay posed on the project, will be used by the astronomical and spectroscopic community as line catalogs, a line by line spectral database, for the identification of the studied molecules in the interstellar medium and in gas-phase chemical reaction systems. The spectral treatment function may be used by a broader community as a way to improve the quality of experimental data, if the experiment applies physics principle similar to the chirped pulse technique.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

The main scientific achievements of this project are the following: (1) the development of a general spectral treatment function that improves signal to noise ratio of chirped pulse spectra; (2) the first laboratory measurement and analysis of 3 important isomers of N-bearing astrophysical molecules, CH2NOH, CH3NO, and (CH3)2CNH (Figures 1 and 2), in the millimeter-wave range; (3) the implementation of the instrument and software and reproduction of radical species CH2CN (Figure 3) and CH3CO.
The results of the spectral treatment function and CH2NOH have been published in top-quality peer-reviewed journals and presented in French and international conferences. The spectrum catalog of CN2NOH generated from experimental results has been uploaded to open-access servers. The results of CH3NO and (CH3)2CNH have been presented in conferences too, and will be submitted to journals before the end of 2022.
The search on radical species (Figure 4), which was the original goal of the project, has not reached the stage of publication due to various delays. Nevertheless, the instrument, already fully integrated and functional, has reached the boundary of the state-of-the-art, as it is one of the very few millimeter-wave chirped pulse spectrometers coupled with supersonic discharge sources in the world. The search on aminogen radicals will continue to be perused by the Lille team, and by me via collaboration with the Lille team in my future research career. And the instrument will stay in Lille and lead future studies of new radical species of astrophysical importance.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The progress of all aspects of the project has been affected by the Covid-19 pandemic, and the ending of the transition period of Brexit caused extra unexpected delays. The main research progress has been executed to ~40% at the end of the project, which is the completion of the spectrometer development, signal optimization, and measurement of radical signals. Considering that the actual start of the spectrometer development was delayed by 1 year, the actual development progress had met some obstacles but in general within expectation. Due to the under-estimation of the difficulty in radical searching, no conclusive aminogen radical signals have been registered by the end of the project, but the system is close to this point with further improvement of the spectrometer sensitivity.
The expected results on the spectra of aminogen radicals and their chemical reaction with OH radical will be the subject of continuous study in the Lille team based on the spectrometer I have developed during the fellowship period.
The impact of the work on the society may be difficult to predict directly, but nevertheless above zero. The newly measured spectra of N-bearing molecules, namely CH2NOH, CH3NO and (CH3)2CNH, may eventually lead to the detection of these molecules in the interstellar medium, expanding our knowledge in the interstellar chemistry network, especially the one lead to the formation of amino-acids. The spectra, not been studied in much detail before, contribute also to molecular database that can be used by researchers in other field for analytical chemistry purpose, i.e. using our data as the method of identification of these molecules. The generalized spectral treatment function may also be adopted by researchers in other relevant fields to improve their signal.
Potential users of the project results are first and mainly the astronomical and spectroscopic community. The already published data, together with the results currently under preparation of submission by the end of 2022, will be of direct access to researchers in these communities in the widely accepted data format in these communities. In addition, in the future, I plan to continue the study of aminogen radicals, and the results are expected to be useful not only to the above communities, but also to a broader audience of chemists and physicists when the future research reveals more unknown properties of these radicals.

Figure 2: Sample experimental spectrum and model of (CH3)2CNH