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Univ. Paris-Saclay

Sujet de stage / Master 2 Internship

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Control of a single molecule fluorescence by an optical nano-antenna

Contact: VASSANT Simon, , simon.vassant@cea.fr, +33 1 69 08 95 97
The objective of the internship is to measure the influence of a nano-antenna on the fluorescence of a single molecule. The experiment consists in approaching the nano-antenna in a controlled way with an atomic force microscope, while measuring the emission of fluorescence photons. The student will perform a mainly experimental work, on a dedicated experimental bench, from the fabrication of the tips to the optical measurements and the data analysis.
Possibility of continuation in PhD: Oui
Deadline for application:01/08/2023

Full description:
The host team is the Nanophotonics group of CEA/SPEC/LEPO. For the needs of its research, the group has developed an important expertise in the coupling of optical measurements with local probe microscopies. The team has several experimental benches of this type, operating in air or under ultra-high vacuum, allowing linear and non-linear optical measurements of nano-objects, and the development of new methods of optical microscopy with active probes... In the framework of the ANR PlasmonISC project (2020-2024), we are interested in the fluorescence emission properties of single molecules in the presence of a nano-antenna.

The objective of this project is to obtain quantitative measurements of the photophysical properties of a single molecule (lifetime, excitation rate, inter-system crossing rate...), in the presence and absence of a nano-antenna. These quantitative experimental measurements will serve as a basis for the theoretical understanding of the molecule-antenna interaction.
The laboratory has an optical measurement bench, dedicated to this project, which allows a wide variety of optical measurements (fluorescence, Raman, scattering, photon counting, correlation function measurement (Hanbury-Brown-Twiss), emission diagram...).

We are working on a molecular system that is simple to prepare, where we insert fluorescent molecules in a thin organic matrix (20-30 nm). To bring the antenna close to the molecule, we opted for atomic force microscopy, which allows a nanometric positioning of the antenna with respect to the molecule. We are currently finalizing a measurement campaign using a pulled optical fiber as an antenna. This glass tip allowed us to observe large effects on fluorescence.

In the framework of the internship, the student will have to carry out a mainly experimental work, which consists in studying the influence of other types of antennas (plasmonic, magnetic, dielectric). The work will focus on the fabrication of the tips (the laboratory has a clean room for this purpose, allowing advanced nano-fabrication techniques), the preparation of samples and optical characterizations of single molecules, with and without antenna. She/he will actively participate in the analysis of the results.

This internship will be an opportunity to learn advanced optical microscopy techniques, nanophotonics concepts at the interface with quantum mechanics, atomic force microscopy techniques, as well as clean room nano-fabrication skills.

A follow-up PhD is possible, under reserve of a financing (CEA, doctoral school, ...).
Technics/methods used during the internship:
Optical microscopy Spectroscopy Atomic force microscopy Chemical functionalization Nanofabrication Clean room Electron microscopy

Tutor of the internship


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