Cutting Edge Lecture in Science
By Bradley J. Siwick (Assistant Professor, Canada Research Chair in Ultrafast Science [Tier II], Chemistry, McGill)
Research in the Siwick laboratory is focused on developing technologies that will allow complex transient structures of molecular and material systems to be determined at the atomic level. In particular, this involves engineering new instruments that unite the tools and techniques of electron microscopy with those of time-resolved (ultrafast) laser spectroscopy in novel ways. They study photoinduced phase transitions in materials (order-disorder and order-order), where it will be possible to directly determine the changes in atomic configuration that accompany the system’s progress along the physical pathway between phases. These techniques are also employed to try and understand structural dynamics in functional light-activated nanocomposite, nanostructured and organic materials. An additional area of research is structural studies of extreme states of matter (i.e. materials under the conditions existing at the core of planets, or plasmas). Extreme conditions can be prepared transiently through interaction with intense laser pulses. Some projects are conducted at the Advanced Laser Light Source (ALLS) facility being constructed in Varennes, Quebec, near Montreal – a world class $21M laser facility that is capable of producing femtosecond pulses of light in a range of wavelengths from the mid-IR to X-ray with peak powers greater than 1014 W.