AppDef for Ellipsometry

[sanbrock]

https://github.com/FAIRmat-Experimental/nexus_definitions/tree/fairmat

[prjemian]

The new definition should be added to the contributed_definitions folder of the definitions repository (in a branch or fork). Once ratified by the NIAC (item 3 of NeXus Constitution), it will be moved to the applications folder.

The pull request should be made to the definitions repository.

[sanbrock]

nexusformat/definitions#997

[cmmngr]

We reused base classes and added fields relevant to ellipsometry experiments, but neither did we modify any existing base classes nor created any new ones.

[prjemian]

Keep in mind that the first line of the <doc> element should be all on one line. It is used on this page to provide a rapid summary of each definition: https://manual.nexusformat.org/classes/applications/index.html#application-definitions
The one-line for ellipsometry could be just the first sentence.

The remainder in the next paragraph (with a blank line between).