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. 2016 Oct 5:6:34266.
doi: 10.1038/srep34266.

Elastic Scattering Spectroscopy (ESS): an Instrument-Concept for Dynamics of Complex (Bio-) Systems From Elastic Neutron Scattering

Antonio Benedetto  1   2 , Gordon J Kearley  3
Affiliations

Elastic Scattering Spectroscopy (ESS): an Instrument-Concept for Dynamics of Complex (Bio-) Systems From Elastic Neutron Scattering

Antonio Benedetto et al. Sci Rep. .

Abstract

A new type of neutron-scattering spectroscopy is presented that is designed specifically to measure dynamics in bio-systems that are difficult to obtain in any other way. The temporal information is largely model-free and is analogous to relaxation processes measured with dielectric spectroscopy, but provides additional spacial and geometric aspects of the underlying dynamics. Numerical simulations of the basic instrument design show the neutron beam can be highly focussed, giving efficiency gains that enable the use of small samples. Although we concentrate on continuous neutron sources, the extension to pulsed neutron sources is proposed, both requiring minimal data-treatment and being broadly analogous with dielectric spectroscopy, they will open the study of dynamics to new areas of biophysics.

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Figures

Figure 1
Figure 1. Relaxation time versus temperature of protein hydration water in Lysozyme measured by neutron scattering.
The relaxation time obtained with the standard quasi-elastic neutron scattering protocol by Chen and co-workers (blue dots), and the one obtained by RENS protocol (red dots) are shown. The RENS data have been obtained by collecting the elastic neutron-scattering intensity with five different neutron spectrometers working at 5 different energy resolution: 0.65 μeV for SPHERES at MLZ, 0.8 μeV for HFBS at NIST, 1 μeV for IN10, 8 μeV for IN13, and 200 μeV for IN4 at ILL. In the current work we present an instrument-concept able to collect RENS-like data, and give then direct access to the system relaxation time. The main target will be complex (bio-) systems.
Figure 2
Figure 2. The primary spectrometer concept.
The different colours represent different wavelength, which also have different energy resolutions.
Figure 3
Figure 3. Instrument layout.
(a) The layout for the CW instrument-concept suitable for continuous sources; and (b) the layout for the TOF instrument-concept suitable for pulsed sources. The different colours represent different wavelengths, which also have different energy resolutions, different velocities and, in turn, different TOF.
Figure 4
Figure 4. The ESS spectra for the CW version: the elastic scattered intensity as a function of the energy resolution for five samples with different quasi elastic widths (relaxation times) as indicated on the plot.
The curves are the best fits of sigmoidal functions (Eq. 11 in ref. 39) of the experimental points. Inset: (a) the ESS spectra as a function of the resolution time in picosecond; (b) the second derivative of the ESS spectra showing a maximum at the energy value that matches the system relaxation time.
See this image and copyright information in PMC

References

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