法国国家科学研究中心（CNRS）物理化学方向博士后

法国国家科学研究中心（CNRS）物理化学方向博士后

Post-Doctoral Position (H/F) : Study Of The Modification Of Fossilized Teeth Under X-Ray Irradiation

Universities And Institutes Of France

Description

Organisation/Company: CNRS

Research Field: Chemistry › Computational chemistry Chemistry › Physical chemistry

Researcher Profile: Recognised Researcher (R2)

Application Deadline: 09/09/2022 23:59 - Europe/Brussels

Location: France › GIF SUR YVETTE

Type Of Contract: Temporary

Job Status: Full-time

Hours Per Week: 35

Offer Starting Date: 01/10/2022

Eu Research Framework Programme: H2020

The post-doctoral fellow will work in the IPANEMA laboratory (UAR3461, CNRS, MC, UVSQ, MNHN) within the framework of the European program IPERION-HS (H2020-INFRAIA-2018-2020 – Grant agreement 871034). This project is part of the research topic defined in task "5.3" of the "Joint Research Activities" work package entitled "Monitoring strategies for safe analysis of heritage artefacts".

We propose to study and understand the effects of chemical modifications generated under X-ray radiation on a corpus of fossil teeth. Tooth fragments unearthed during archaeological and paleontological excavations are useful for the direct assessment of biodiversity and past paleodiets. The extraction of this information is increasingly based on the use of synchrotron X-ray spectro-imaging approaches, and in particular on X-ray tomography, which provides access to the growth lines of the teeth, linked to age and seasonality. X-ray fluorescence (XRF) and absorption (XAS) spectroscopy can probe the chemical compositions associated with their development, burial and diagenetic environment. However, the use of intense X-ray beams can generate changes in the composition of organic and inorganic phases of dental tissues, and raises new concerns about experimental conditions and the accuracy of data interpretation. This postdoctoral project will focus on developing strategies for detecting early manifestations of chemical changes induced by X-ray techniques on fossil teeth. In particular, it will integrate the following four aspects: 1) The study of changes of optical properties of the sample, such as changes in color or the appearance of luminescence, which could be observed with in- situ luminescence techniques using detection devices such as those available on the PUMA beamline at the SOLEIL synchrotron. For example, the evolution of color centers will be monitored using multispectral imaging. 2) The study of non-observable modifications, such as speciation changes due to photooxidation or -reduction of atoms under the beam by original approaches for collecting speciation data (µ-XAS) to better understand the impact of oxidation-reduction sensitive transition metals and rare earths in discolorations. 3) Post-irradiation analyzes (e.g. photoluminescence, SHG, and FTIR micro- spectroscopy) will be used to assess the impact of the main experimental parameters (dose, energy, %RH) on the collagen phases. 4) Finally, the evaluation, speciation imaging strategies by sparse imaging will be explored by prior modeling of the beam/material interaction, either by combining real-time tracking and information content optimization, an approach to exotic spatial scanning and the implementation of an in situ de-trapping approach.

The knowledge gained from this work will be essential in mitigating the risks associated with the use of high-flux X-ray techniques. In particular, they will allow better interaction with museum curators, so as not to affect the visual appearance of specimens in collections, and will also strengthen the robustness of the data collected by scientists, who want to ensure that the chemical information obtained were not altered by X-ray induced processes.

In conclusion, this post-doctorate aims to improve knowledge on the reaction mechanisms of biomineralized systems altered over a long time, such as fossil teeth. As a corollary, the process aims at improving the detection systems during irradiation and a posteriori as well as the collection processes aimed at reducing the doses deposited while maintaining a high quality of data.

The main objective of this post-doctorate is to study the modifications induced by X-ray radiation on the physico-chemical properties and visual appearance of fossil teeth.

The position is funded by the IPERION-HS program (Integrating Platforms for the European Research Infrastructure ON Heritage Science – H2020-EU.1.4.1.2. - Integrating and opening existing national and regional research infrastructures of European interest – Grant agreement ID: 871034) .

The postdoctoral researcher will be part of a multidisciplinary team, which includes doctoral students, trainees and young researchers, for whom he/she may be asked to provide partial supervision. A research and service unit, IPANEMA is the European platform for research on ancient materials (CNRS, Ministry of Culture and Communication, University of Versailles Saint-Quentin-en-Yvelines), located on the site of the SOLEIL synchrotron ( Saclay plateau, region south of Paris). IPANEMA is unique in the world in that it is exclusively devoted to the study of ancient materials (materials from archaeology, paleo-environments, paleontology and cultural heritage) and located on a large instrument. IPANEMA supports scientists who study ancient materials, and develops its own research activities, which focuses on advanced imaging and spectroscopic analysis of ancient materials, and statistical data processing.

Eligibility criteria

Knowledge of physics, materials science or inorganic chemistry is required. Experience with optical, IR, synchrotron instrumentation or dosimetry is a plus, as well as a strong taste for teamwork in an interdisciplinary field.

Web site for additional job details

https: // emploi.cnrs.fr/Offres/CDD/UAR3461-REGOPR-019/Default.aspx

Required Research Experiences

RESEARCH FIELD

Chemistry › Physical chemistry

YEARS OF RESEARCH EXPERIENCE

1 - 4

RESEARCH FIELD

Chemistry › Computational chemistry

YEARS OF RESEARCH EXPERIENCE

1 - 4

Offer Requirements

REQUIRED EDUCATION LEVEL

Chemistry: PhD or equivalent

REQUIRED LANGUAGES

FRENCH: Basic

Contact Information

Organisation/Company: CNRS

Department: Institutphotoniqued'analyse non-destructive européen des matériauxanciens

Organisation Type: Public Research Institution

Website: https:// ipanema.cnrs.fr/

Country: France

City: GIF SUR YVETTE