xpstrace: X-ray photoelectron spectroscopy parser

The xpstrace parser handles the reading and processing of x-ray photoelectron spectroscopy files. The basic function of the parser is to:

1. read in the raw data and create timestamped traces

2. collect metadata such as measurement settings, software, operator etc.

Usage

The use of xpstrace can be specified using the "parser" keyword in the schema. Further information can be specified in the "parameters" (dict):

• "tracetype" (str): The file type of the raw data file. See here for details.

Provides

The primary functionality of xpstrace is to load x-ray photoelectron spectroscopy data, including determining uncertainties of the signal (y-axis), as well as explicitly populating the points in the energy axis (E). This raw data is stored, for each timestep, in the "raw" entry using the following format:

- raw:
    traces:
      "{{ trace_number }}":   # number of the trace
        name:          !!str  #
        atomic_number: !!str  #
        dwell_time:    !!str  #
        e_pass:        !!str  #
        description:   !!str  #
        E:                    # energies are always in eV
          {n: [!!float, ...], s: [!!float, ...], u: "eV"}
        y:                   # y-axis units from file
          {n: [!!float, ...], s: [!!float, ...], u: !!str}

The uncertainties "s" in "E" are taken as the step-width of the linearly spaced energy values.

The uncertainties "s" of "y" are currently set to a constant value of 12.5 counts per second as all the signals in the files seen so far only seem to take on values in those steps.

TODO

https://github.com/dgbowl/yadg/issues/13

Determining the uncertainty of the counts per second signal in xps traces from the phispe parser should be done in a better way.

In general, the "metadata" collected from the raw file will depend on the "tracetype". The following metadata entries are definitely stored in the "params" element of each step:

params:
  software_id:  !!str  # software name
  version:      !!str  # software version
  username:     !!str  # operator