Photophysical characterization of single molecules in thin films

Full description

In two research projects, our team is studying the photo-physics of fluorescent organic molecules with strong potential for optoelectronics and biophysics.

• Project PlasmonISC: This project focuses on the study of isolated fluorescent molecules capable of emitting single photons, paving the way for applications in quantum cryptography and high-precision imaging (https://anr.fr/Projet-ANR-19-CE09-0009).
• Project LESOMMETA: This project explores more complex assemblies of molecules, capable of forming liquid crystals and presenting two distinct emitting groups in the visible spectrum. The aim is to study how these molecules interact and to understand their photo-physical dynamics (https://anr.fr/Projet-ANR-21-CE06-0041).

In both cases, analysis of the optical properties of these molecules requires their immobilization in a thin polymer film, whose thickness varies between 5 and 30 nm. To this end, we have developed extensive experimental know-how in the laboratory, including the use of confocal microscopy, fluorescence, absorption and Raman spectroscopy, as well as auto-correlation measurements (Hanbury-Brown-Twiss), polarization analyses and studies as a function of excitation power.

A recent example of our work is available on the HAL platform, illustrating our expertise in molecular characterization (https://hal.science/hal-04585254).

Role and mission:

The candidate will be responsible for manufacturing thin polymer films in our cleanroom, using the spin-coating technique. After fabrication, the student will characterize these films to determine their thickness using an atomic force microscope (AFM) and/or a profilometer.

Once the films have been made, they will be doped with the molecules of interest, then subjected to a series of optical characterizations designed to assess the photo-stability and photophysical properties of the molecules: emission spectra, lifetime, purity of single-photon emission, spatial orientation of the molecules, and signal-to-noise ratio.

Skills and learning :

This internship offers the opportunity to:

• Learn classic cleanroom micro/nano-fabrication techniques, with a particular focus on spin-coating deposition.
• Acquire solid skills in experimental optics, thanks to the use of a dedicated measurement bench and high-precision instruments.
• Understand the principles of fluorescence spectroscopy and molecular characterization techniques, including the study of the photophysical properties of single molecules.
• Work in a stimulating research environment, with opportunities for integration into cutting-edge research projects.

Location

CEA-Saclay, Orme des merisiers, 91 Essone, France

Internship conditions

• Internship duration: 6 months
• Level of study: Bac+4/5
• Training: Master 1
• Continuation in PhD thesis: Yes
• Application deadline: 4 novembre 2024

Useful methods and technics:

• Spin-coating
• Cleanroom nanofabrication
• Atomic Force Microscopy (AFM)
• Confocal microscopy
• Spectroscopy
• Time-resolved photon counting and detection statistics

Computer languages and software:
Python

Supervisor

Simon Vassant
Phone: +33 1 6908 9597
Email :

Head of the laboratory SPEC / LEPO

Ludovic Douillard
Phone: +33 1 6908 0836