Our initiative aims at establishing a common data and metadata standard for photemission spectroscopy experiments. Building on the NeXus file format, we are developing a common dictionary for metadata description and universal file format for multidimensional ARPES data such as generated by hemispherical electron analyzers, photoelectron or momentum microscopes. Building on this unifying file format for data and metadata description at both lab sources and large scale facilities we are developing platforms for data sharing following the FAIR principle and common data visualization and analysis tool kits building on specific application definitions.
The general outline of our approach is summarized in the following schematic:
Both the experimental raw data and meta data (automatically or manually generated) are translated by a parser program to the NXmpes format, by matching entries against the standardized parameter dictionary, to ensure consistency of nomenclature between different setups. In addition, application definitions derived from NXmpes can be applied that require certain parameters to be present for a file to qualify for a given application. The organized data and metadata, stored as a NeXus file can be shared and accessed by universal tools according to the application definitions.
While the NXmpes base class aims at allowing to describe any possible multidimensional ARPES setup, a concrete setup and application potentially only utilizes a subset of these definitions, as sketched in the figure above. Examples for regular ARPES, time-resolved ARPES and spin-resolved ARPES each use specific sub-sets of the base class.
Our core codebase is being developed at: https://github.com/OpenCOMPES/mpes-nexus