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

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

Aug 16, 2023 241 likes •332 views

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,

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SLIDE 1

10 10

1

10

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10

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Energy [meV]

1x10

  • 11

1x10

  • 12

1x10

  • 13

1x10

  • 14

1x10

  • 15

1x10

  • 16

1x10

  • 17

Neutrons

VIS, UV, X-ray (not precisely equivalent)

Photons

Brillouin, THz & Raman Spectroscopy Infrared & Raman Spectroscopy Deep Inelastic Single-particle (Compton) Scattering Inelastic (lattice & intramolecular modes) Quasielastic (diffusion / tunnelling)

1x10

  • 7 to

1x10

  • 11

elastic line

Timescales [sec]

IRIS OSIRIS

Chemical Spectroscopy at ISIS

Low energy (Bril rillo louin, in, THz) High energy (Compt pton) n)

Simultaneous neutron diffraction

MAPS PS

In-situ Raman Complex sample environments (adsorption, catalysis …)

Interm rmediat diate energy (Raman an )

Computational modelling

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SLIDE 2

eV Neutron Spectroscopy a Decade Ago

Phys Rev Lett 89 135505 (2002)

  • Detailed information on proton tunnelling dynamics

from single crystals.

  • Access to effective PES in favourable circumstances.
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SLIDE 3

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)

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SLIDE 4

Increasingly Complex Materials

  • 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)

Neutron Diffraction

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SLIDE 5

Towards MAss-selective Neutron SpEctroscopy

  • 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)

LiF+Al LiH+Al LiD+Al

forward scattering back scattering

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SLIDE 6

Overview

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

TODAY TOMORROW

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SLIDE 7