Joseph Sanderson

Dr. Joseph (Joe) Sanderson's research and that of his students, focuses on the study of how matter interacts with intense Femtosecond laser pulses. One of the ways which the interaction of matter with femtosecond laser pulses can be utilized is as a means of imaging some of the smallest, fastest moving, and most complex units of matter - molecules. 

• Femtosecond laser interaction with matter for:
• Coulomb imaging of small molecules
• 2D material modification for device and Analytical Methods
• Nanoparticle generation

Coulomb imaging:

In Coulomb imaging lab and at the Advanced Laser Light Source (ALLS) laboratory, researchers can use the two most important properties of a femtosecond laser pulse:

• Its tiny duration (1fs=one thousand million millionths of a second, which is inconceivably short to a human being but is quite normal for molecules which are used to vibrating on this kind of timescale)
• And its high intensity (this is partly a consequence of the shortness of the pulse because intensity is power divided by area, and power is energy divided by the pulse duration).

The pulse length acts like the shutter speed of a camera allowing them to take a snapshot of a molecule in motion and the intensity gives us a means to make the image.

The high intensity is used to rip many electrons from the molecule (the laser light develops a momentary electric field stronger than the one which binds the electrons to the atoms) which then explodes because there are not enough electrons left to bind the positively charged atomic ions together. This is called a Coulomb explosion after the physicist, Charles de Coulomb, who gave his name to the electrostatic force between two charged objects.

To use this explosion as a way of imaging the molecule, all of the fragment ions created must be detected and their momentum measured, from which the original geometry of the molecule is determined by working backward.

Femtosecond laser induced Nano particle production:

Nano particle production and characterization is now one of the hot topics in science, engineering, and industry. Perhaps surprisingly, given its ability to disrupt matter by rapidly removing many electrons from anything in its way, femtosecond laser pulses have recently been shown to be a highly promising tool in generating nano particles. In fact, it's precisely this disruptive capability which is the quality which promotes the nano particle production.

When femtosecond laser pulses interact either with a liquid or a solid, they cause the material to be rapidly reduced to ionized atomic and molecular fragments. These fragments can then self-organize to form either nano scale surface features (which dramatically modify the properties of a material), or nano particles of varying sizes and properties.

One of the nicest particles is a polyyne chain which consists of carbons bound to each other and capped at each end by a hydrogen atom. These chains have been found to have extraordinary properties such as strength beyond that of diamond (also made of carbon). Usually, polyynes are produced from graphite powder (soot) in a liquid heated by an electric discharge or high energy laser pulse. Recently, it has been found that instead of this messy method, it is possible to take a clean solvent solution and irradiate it with pulses from a femtosecond laser. The result is a solution containing polyynes and other fragments of the initial solvent.

One of the ways that the femtosecond laser is able to process the liquid effectively is by generating a bright filament, in which nonlinear interactions between the laser field and the liquid increase the length of the focus by orders of magnitude.

• 1991 PhD Physics, University College, London, UK

• 1986 BSc Physics & Astronomy, University College, London, UK

• 2009, JSPS Fellowship

• 2003, Premiers research Excellence Award Senior

• 2012 - 2013: Making Groups Work for Large Classes and Assessing Their Impact

• Faculty, Centre for Advanced Materials Joining

• Principal Investigator, Nano and Micro Systems Lab
• Principle Investigator Waterloo ALLS Reaction Microscope Facility
• Principle Investigator Waterloo Femto-lab Laser Facility

• PHYS 111 - Physics 1
  • Taught in 2019, 2020, 2021, 2022, 2023
• PHYS 256 - Geometrical and Physical Optics
  • Taught in 2020, 2022, 2023
• PHYS 260L - Intermediate Physics Laboratory
  • Taught in 2019
• SCI 238 - Introductory Astronomy
  • Taught in 2024

Note: Only courses taught in the past 5 years are displayed.