Motofit_reference.pdf
Motofit.ipf

5 Jul 2005

Dr. Andrew Nelson
<Andrew.Nelson@ansto.gov.au>

I have developed a set of functions that aids the fitting of neutron and X-ray specular reflectivity data.

Specular reflectivity is defined as the ratio of reflected intensity over incident
intensity, where the angle of reflection (q) is equal to the angle of incidence.

The specular reflectivity is calculated using the ParrattŐs recursion formula 1 for
stratified thin films, as a function of the perpendicular momentum transfer, Qz.

     4pi
Q = ------ sin(theta)
 z  lambda

Motofit is an IGOR Pro macro that aids the fitting of specular X-ray and neutron reflectivity data.

Motofit works within the analysis package IGOR PRO (Wavemetrics, OR). It was created
in version 4 of IGOR, and should work in version 5.

Why is it called Motofit? Well Moto is the name of a Parrot!

Motofit was created with the aim of allowing a scientist to easily fit her/his reflectivity
data. Other reflectivity packages are obviously out there, but sometimes they donŐt
allow you to do what you want.

The advantage with Motofit/IGOR is that if the user has a specific requirement for the
fit then he/she should be able to code it rather simply.

For example, if you want to fit an analytical profile, then you write a Fitfunc that
will describe your profile. Or perhaps you want to fit with a different resolution
function, it would be easy to include that as well.

You can then send your special function to other users. If everyone does that then a
wide variety of different capabilities can be built up.

For more information, see the Motofit_reference.pdf file.
For more about neutron reflectometry, see http://physchem.ox.ac.uk/~rkt/techniques/nrmain.html