Delphine Bouilly and her team assemble ultra-miniature electronic circuits and sensors to explore the dynamics of the interactions between biological molecules (DNA and proteins) or the fluctuations within a single molecule. The goal is to develop new tools to identify biomarkers associated with various types of cancer and to improve our understanding of the mechanics of basic macromolecules.

My research activities focus on the application of quantum mechanics for calculating material properties. I am interested in several fields, but at present I am concentrating on developing new organic materials for photovoltaic applications, understanding high-temperature superconductor properties using the ab initio approach, and studying nanomaterials such as nanotubes.

I use a theoretical approach that calls on supercomputer capacities to simulate the materials studied. These methods are on the cutting edge of recent developments, like density-functional theory and methods based on Green's function.

When a semiconductor material absorbs a photon, an electron is excited into the conduction band, leaving a hole in the valence band. The Coulomb interaction between the electron and the hole generates a bound state called an exciton, which largely controls the optical properties of semiconductors. In addition, when the environment is structured on a nanometric scale, the optical response of the semiconductors is radically altered by quantum confinement.

My research program revolves around the dynamics of excitons when they are created in nanostructured environments, so as to describe how the energy is absorbed and redistributed as part of a representation in terms of collective excitations. Although the subject is fundamental in nature, it is closely related to the development of excitonics, an emergent field that aims to design and manufacture better optical devices for applications ranging from lighting to quantum computing.

My research program examines the general theme of computational physics of materials. We use powerful computers to probe the structural and other behaviour and properties of materials, and the "structure-function" relationship. Our preferred approach is molecular dynamics, which involves integrating the equations of motion of a system of atoms under the effect of forces from "potentials"; they may be generic (Lennard-Jones, for instance), empirical or semi-empirical, or even ab initio. The size of the systems depends on the potential used and varies from tens or hundreds of atoms to several million.

We study a vast range of problems, but we are particularly interested in the following ones, just as an example: (i) laser ablation and laser-material interactions; in this case we are trying to understand how matter reacts to powerful, short laser pulses - ejection mechanisms, structural modifications of the target, properties of the ablation plume, etc. (ii) disordered, amorphous or vitreous materials; in this field, we are trying to understand the short-, medium- and long-term structure of materials like amorphous silicon, metallic glass, etc. (iii) thermal properties of nanoscopic materials; we are trying to determine how heat dissipates near nanometric structures and how it moves in molecular junctions between nanoparticles, in particular.

My work deals with the computational study of the behaviour of matter at the atomic level. I am interested in how proteins are assembled into neurotoxic structures associated with degenerative diseases like Alzheimer's and Parkinson's. I also study the formation of nanostructures, such as the assembly of silicon nanowires under a gold droplet and the relaxation of disordered systems like glass and amorphous materials. All these systems are characterized by evolution at the atomic level over long periods, i.e. seconds or more. To be able to track this evolution, I am also working on the development of accelerated algorithms for following atomic movements over experimental times. The algorithms developed in my group are among the most efficient in the world, allowing us to study phenomena that are otherwise not easily accessible.

I am also interested in energy and natural resources issues, from shale gas and crude oil to mining resources. I have published a number of books for the general public on the topic, and supervised some students in this field.

In addition, I host a popular science program called La Grande Équation, broadcast on Radio Ville-Marie.

Lastly, I hold the Canada Research Chair in Computational Physics of Complex Materials.

I study the modification and analysis of materials by MeV energy ion beams, to better understand the structure of matter and for fun.

Ion implantation is a technique for modifying the surface of materials by injecting precise quantities of atoms at the desired depth. It is widely used in doping semiconductors when manufacturing very large-scale integrated circuits (VLSI). Since it is a highly out-of-balance phenomenon (the incident atoms typically have energies millions of times higher than the atoms in the material), this implantation often generates new structures at the atomic level that can be exploited to improve the performance of high-tech materials, or may create problems to be overcome.

For instance, during the doping process, implantation creates defects in semiconductors by displacing crystal atoms, and this is damaging to integrated circuits. If there are not too many defects, the damage can be corrected by annealing and the dopant activated. If the density of the defects exceeds a certain threshold, however, permanent damage will appear in the materials and may make the devices unusable.

Inversely, ion implantation generates defects that can be used to modify materials. Implantation makes it possible to create defects near the surface that can later diffuse throughout the material and modify the composition of the lower layers by interdiffusion. In this way it is possible to change the emission wavelengths of quantum dots or wells and the properties of the magnetic layers.

Ion beams can also be used for highly sensitive quantitative measurement of the deep distribution of atoms in a material. In our laboratories we use various ion beam analysis techniques, in particular elastic recoil detection (ERD), a technique developed in our laboratories in the 1970s, and Rutherford backscattering spectrometry (RBS), RBS channelling and nuclear resonant reaction analysis (NRRA).

Professor Stafford's work aims to set up a new platform devoted to the physicochemistry of cold plasmas highly reactive to atmospheric pressure and their applications to the synthesis and functionalization of materials and nanomaterials.