Université de Fribourg

Temporal mapping of photochemical reactions and molecular excited states with carbon specificity

Wang, K. ; Murahari, P. ; Yokoyama, K. ; Lord, J. S. ; Pratt, F. L. ; He, J. ; Schulz, Leander ; Willis, M. ; Anthony, J. E. ; Morley, N. A. ; Nuccio, Laura ; Misquitta, A. ; Dunstan, D. J. ; Shimomura, K. ; Watanabe, I. ; Zhang, S. ; Heathcote, P. ; Drew, Alan J.

In: Nature Materials, 2017, vol. 16, no. 4, p. 467–473

Photochemical reactions are essential to a large number of important industrial and biological processes. A method for monitoring photochemical reaction kinetics and the dynamics of molecular excitations with spatial resolution within the active molecule would allow a rigorous exploration of the pathway and mechanism of photophysical and photochemical processes. Here we demonstrate that...

Université de Fribourg

Muonium avoided level crossing measurement of electron spin relaxation rate in a series of substituted anthradithiophene based molecules

Han, S. ; Wang, K. ; Willis, M. ; Nuccio, Laura ; Pratt, F.L. ; Lord, J.S. ; Thorley, K.J. ; Anthony, J. ; Drew, A.J. ; Zhang, S. ; Schulz, Leander

In: Synthetic Metals, 2015, vol. 208, p. 39–42

Muon spin spectroscopy and in particular the avoided level crossing technique is introduced, with the aim of showing it as a very sensitive local probe for electron spin relaxation in organic semiconductors. Avoided level crossing data on tert-butyl-ethynyl anthradithiophene, tri-methyl-silyl-ethynyl anthradithiophene and tri-ethygermyl-ethynyl anthradithiophene at different temperatures are...

Université de Fribourg

Future directions of μSR—laser excitation

Yokoyama, K. ; Murahari, P. ; Heathcote, P. ; Nuccio, Laura ; Lord, J. S. ; Morley, N. A. ; Drew, Alan J.

In: Physica Scripta, 2014, vol. 88, no. 6, p. 068511

We discuss the general principles of laser-excited muon pump–probe spin spectroscopy (photo-μSR), including the historical origins of the technique, and discuss the overall experimental method. We review examples of past work using this technique, then discuss the future upgrade of the HiFi spectrometer with a high-power laser system. In particular, we note that performing photo-μSR...

Université de Fribourg

Muon spin rotation study of magnetism and superconductivity in Ba(Fe1−xCox)₂As₂ single crystals

Bernhard, Christian ; Wang, Chen Nan ; Nuccio, Laura ; Schulz, Leander ; Zaharko, O. ; Larsen, J. ; Aristizabal, C. ; Willis, M. ; Drew, Alan J. ; Varma, G. D. ; Wolf, T. ; Niedermayer, Ch.

In: Physical Review B - Condensed Matter and Materials Physics, 2012, vol. 86, no. 14, p. 144112

Using muon spin rotation (μSR) we investigated the magnetic and superconducting properties of a series of Ba(Fe1−xCox)₂As₂ single crystals with 0≤x≤0.15. Our study details how the antiferromagnetic order is suppressed upon Co substitution and how it coexists with superconductivity. In the nonsuperconducting samples at 0