Paramagnetic muon states in mesoporous carbon materials

13th International Conference on Muon Spin Rotation, Relaxation and Resonance

Macrae, R.M.^1 ; Upchurch, C.^1 ; Rose, D.K.^1 ; Miyake, Y.^2,3 ; Koda, A.^2,3 ; Lord, J.S.^4 ; Shuttleworth, P.S.^5,6

School of Mathematics and Sciences, Marian University, 3200 Cold Spring Road, Indianapolis

IN

46222, United States^1

Muon Science Section, Materials and Life Science Division, J-PARC Center, 2-4 Shirane, Shirakata, Tokai-mura, Naka-gun, Ibaraki

319-1195, Japan^2

Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki

305-0801, Japan^3

ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire

OX11 0QX, United Kingdom^4

Green Chemistry Centre of Excellence, Department of Chemistry, University of York, York

YO10 5DD, United Kingdom^5

Polymer Physics Group, CSIC, Madrid

28006, Spain^6

关键词: Graphitic materials;    High-temperature pyrolysis;    Hydrophilic materials;    Hydrophobic Material;    Hyperfine constants;    Longitudinal fields;    Low temperatures;    Mesoporous carbon materials;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/551/1/012040/pdf
DOI  :  10.1088/1742-6596/551/1/012040

来源: IOP

【 摘 要 】

We present results of longitudinal field repolarisation measurements carried out at J-PARC and ISIS on the "green" functional carbon materials Starbon 300 and Starbon 800, synthesized using starch as a template and subjected to pyrolysis treatments at different temperatures (300°C and 800°C respectively); pyrolysis at low temperature may be expected to yield a material retaining more of the "hydrophilic" properties of the original starch material in its chemically active voids, while high temperature pyrolysis may be expected to lead to "hydrophobic" voids and a more graphitic material. The hydrophilic material shows a larger repolarising fraction than the hydrophobic material, with a hyperfine constant on the order of 200-300 MHz. This is likely to be a superposition of the repolarisation of multiple radicals. Several candidate and model species are investigated through accompanying density functional theory calculations.