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Iain McKenzie

Research Scientist, Centre for Molecular and Materials Science, TRIUMF
4004 Wesbrook Mall, Vancouver, B.C., Canada V6T 2A3

Adjunct Professor, Department of Chemistry, Simon Fraser University
8888 University Drive, Burnaby, B.C., Canada V5A 1S6

Telephone: 604-222-7386
Fax: 604-222-1074
Email: iain.mckenzie@triumf.ca

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Research

My research involves using spin-polarized, radioactive probes (muons and 8Li+) and the corresponding magnetic resonance techniques (muon spin rotation, relaxation and resonance (µSR) and beta-detected NMR (βNMR), respectively) to study dynamics in soft matter, lithium ion diffusion in battery materials and the structure and reactivity of free radicals. My research covers a wide range of topics bridging chemistry and condensed matter physics. The experiments are carried out at large-scale facilities in Canada (TRIUMF), the U.K. (ISIS) and Switzerland (PSI). Some of my active research projects are listed below.

Depth Dependence of Polymer Dynamics

Thin films have very different properties from their bulk forms due to the effects of reduced dimensions and interfaces. The reduction of the glass transition temperature in polymer films less than ~40 nm thick has been explained in terms of a near-surface region with faster dynamics than the bulk material, but direct experimental evidence for this had been lacking. I have used βNMR of implanted 8Li+ to study the depth dependent dynamics of polystrene near a free surface and provided the best evidence for a thin region near the surface approximately 10 nm thick with enhanced dynamics compared with the bulk. (Soft Matter (2015) 11, 1755 and Soft Matter (2018))

Lithium Ion Diffusion in Battery Materials

Meeting our climate change goals requires drastic improvements in battery technology. A crucial part of Li-ion batteries (LIB) is the electrolyte, and a better understanding of the microscopic process of Li+ diffusion within the electrolyte is needed to improve LIB performance. Poly(ethylene oxide) (PEO)-based electrolytes are being investigated for applications in LIB due to their large ionic conductivities. I have used βNMR to study lithium ion diffusion in thin films of PEO and PEO containing salts such as as lithium bis(trifluoromethane)sulfonimide (LiTFSI) (J. Am. Chem. Soc. (2014) 136, 7833 and J. Chem. Phys. (2017) 146, 244903). I have also been involved in measurements of 8Li+ dynamics in rutile TiO2 (Chem. Mater. (2017) 29, 10187).

Structure and dynamics of free radicals using muon spin spectroscopy

The positive muon (µ+) can be incorporated into free radicals where it acts as a probe of the structure and dynamics. The muoniated radicals are characterized by a series of magnetic resonance techniques known as µSR for muon spin rotation, resonance and relaxation spectroscopy. I have used µSR to study several isotope effects on several novel chemical species including the methyl radical and Mu adducts of stable carbenes. (Annu. Rep. Prog. Chem., Sect. C: Phys. Chem. (2013) 109, 65) I have recently been studying the reaction of Mu with organometallic compounds such as ferrocene (Phys. Chem. Chem. Phys. (2014) 16, 10600) and ruthenocene (Can. J. Chem. (2018) 96, 358).

Spin probes in soft condensed matter.

Muoniated radicals can be used as spin probes in a variety of soft matter systems. I have used µSR to study partitioning of cosurfactants in bilayers and micelles (Phys. Chem. Chem. Phys. 2006, 8, 4723 and Phys. Chem. Chem. Phys. 2017, 19, 9551) and microscopic dynamics in calamitic (rod-like) (J. Phys. Chem. B (2011) 115, 9360) and discotic liquid crysals (Phys. Rev. E (2013) 87, 012504). Muoniated radicals are very sensitive to the polarity of the local environment and the amplitude of fluctuations in anisotropic environments. I am currently using this technique to study the local environment and dynamics of cholesterol in model biological systems. Another useful probe is the F-Mu+-F state, which I have used to study near-surface dynamics in PTFE (Phys. Rev. E (2014) 89, 022605)

Computational chemistry of free radicals

I use density functional theory (DFT) calculations to study muoniated and conventional free radicals. My current interest in this area is organic semiconductors (OSCs) where several groups have claimed that µSR can be used to measure the intrinsic electron hopping rate or provide information about the electron spin relaxation rate. I have shown that Mu addition to Alq3 changes the energy levels and pins the unpaired electron meaning that the claim to have measured the intrinsic electron hopping rate is incorrect. (J. Phys. Chem. A (2010) 114, 12759).

Employment History

Education

  • B.Sc.(Honours) Chemistry, Simon Fraser University, 1999

  • Ph.D Chemistry, Simon Fraser University, 2004. Supervisor: Prof. Paul W. Percival

Other Interests

The most important thing for me is to spend time with my wife, Anna, and our three children. I enjoy snowboarding, volleyball, camping, hiking, reading about history and travelling.


Centre for Molecular and Materials Science
TRIUMF
4004 Wesbrook Mall
Vancouver, B.C. Canada V6T 2A3