Chemical Spectroscopy at ISIS High energy (Compt pton) n) - PowerPoint PPT Presentation

Chemical Spectroscopy at ISIS High energy (Compt pton) n) Timescales [sec] -7 to 1x10 -11 -12 -13 -14 -15 -16 -17 1x10 1x10 1x10 1x10 1x10 1x10 1x10 -11 1x10 Photons Brillouin, THz & Raman Infrared & Raman VIS, UV, X-ray Spectroscopy Spectroscopy (not precisely equivalent) Simultaneous neutron diffraction Inelastic (lattice & intramolecular modes) MAPS PS Neutrons Interm rmediat diate energy Deep Inelastic (Raman an ) Single-particle (Compton) Scattering Quasielastic (diffusion / tunnelling) elastic 0 1 2 3 4 5 6 10 10 10 10 10 10 10 line Complex sample Energy [meV] environments IRIS (adsorption, catalysis …) OSIRIS In-situ Raman Computational modelling Low energy (Bril rillo louin, in, THz)

eV Neutron Spectroscopy a Decade Ago • Detailed information on proton tunnelling dynamics from single crystals. • Access to effective PES in favourable circumstances. Phys Rev Lett 89 135505 (2002)

Disordered Matter and First-principles Modelling • Nuclear quantum dynamics of D and O in intrinsically disordered media. • Key: use of state-of-art first-principles methods (PIMD, etc). J Phys Chem Lett 4 3251 (2013)

Increasingly Complex Materials Neutron Diffraction • Calculations to interpret Compton profiles – harmonic approximation is a good starting point. • Access to structure of adsorbate complex, coverage dependence of adsorbate-adsorbate interactions. Faraday Discuss 151 171 (2011)

Towards MA ss-selective N eutron S p E ctroscopy LiD+Al LiH+Al LiF+Al forward scattering back scattering • MANSE: element specific, sensitive to light nuclides, no isotopic substitution, not restricted to low Ts , … • Establish realm of applicability: mass discrimination, range and sensitivity, information content of experimental data, link to materials properties. • Explore experimental and modelling requirements. Phys Rev B 83 134305 (2011) JPCM 24 365401 (2012) Phys Rev B 88 184304 (2013)

Overview TODAY TOMORROW Proton quantum dynamics Computational tools and predictions Heavier nuclei Materials Wrap-up Experimental tools and analysis