Hall-Ross

Description

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

The Hall-Ross Jump diffusion model [1] has the form:

Gamma(Q)=τ(1exp(l2Q22))

Units of l are inverse units of Q.

Units of Gamma are meV if units of τ are ps. Alternatively, units of Gamma are μeVifunitsof:math:tau` are ns.

Mean square diffusion jump length =3l2 2.

Diffusion coefficient D=l22τ 2ps1.

Properties (fitting parameters)

Name

Default

Description

Tau

1.0

Residence time

L

0.2

Standard deviation of jump lengths

References

Categories: FitFunctions | QuasiElastic

Source

Python: HallRoss.py