A peak inside water Prof. Sir John Enderby P r o f . P e t - PowerPoint PPT Presentation

A “peak” inside water Prof. Sir John Enderby P r o f . P e t e r E g e l s t a f f Alan K Soper FRS, ISIS Facility, STFC Rutherford Appleton Laboratory, UK

First order difference method Alan K Soper FRS

Scattering neutrons off water – reactor neutron source. The Institut Laue Langevin reactor, Attempt to use hydrogen isotopes: Grenoble. - Large recoil effect... D4C instrument at ILL Alan K Soper FRS

To solve the recoil problem: 1) Go to a pulsed neutron source. 2) Use high neutron energies, small scattering angles. 3) Use a third (mixture) sample. Alan K Soper FRS

1) Go to a pulsed neutron source. Alan K Soper FRS

2) Use high neutron energies, small scattering angles. Alan K Soper FRS

3) Use a third (mixture) sample. Alan K Soper FRS

Introduce EPSR computer simulation... ● Aim: to get a structural model of the system being studied. ● Method: Like computed tomography. ● Data act as constraint on structure, but do not define it. Alan K Soper FRS

Sorbitol in Water at 100K Before After Alan K Soper FRS

Method is taking off! Polyethylene oxide... Water under pressure Water in MCM41 pores AOT/Isooctane reverse micelles Alan K Soper FRS

Water under pressure 0.3 kbar Alan K Soper FRS

Water under pressure 2.1 kbar Alan K Soper FRS

Water under pressure 4.0 kbar Alan K Soper FRS

Water in MCM41 pores Alan K Soper FRS

AOT/Isooctane reverse micelles Alan K Soper FRS