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Chudley-Elliot¶

Description¶

Models the Q dependence of the QENS line width (Gamma (hwhm)), diffusion coefficients (D), residence times (tau) and jump lengths (length) to extract the associated long range diffusive motions of molecules.

The Chudley-Elliot Jump diffusion model [1] has the form:

\[HWHM(Q) = \frac{\hbar}{\tau} \cdot \left(1 - \frac{sin(Ql)}{Ql}\right)\]

Units of \(l\) are inverse units of \(Q\).

Units of \(HWHM\) are \(meV\) if units of \(\tau\) are ps. Alternatively, units of \(HWHM\) are \(\mu eV\) if units of \(\tau\) are ns.

Properties (fitting parameters)¶

Name	Default	Description
Tau	1.0	Residence time
L	1.5	Jump length

References¶

[1]	C T Chudley and R J Elliott 1961 Proc. Phys. Soc. 77 353

Categories: FitFunctions | QuasiElastic

Source¶

Python: ChudleyElliot.py