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 (last modified: 2019-02-08)