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28. Wavelength Spectra

Wavelength spectra — UV, DAD, and other electromagnetic-radiation (EMR) spectra --- are stored independently from mass spectra so the two modalities can have divergent schemas without inflating the number of empty columns, and so a reader need not sift through mass spectra to find EMR spectra (or vice versa). These files SHOULD be present only if wavelength spectra are included in the archive.

28.1 Wavelength spectrum signal data — wavelength_spectra_data.parquet

{
  "name": "wavelength_spectra_data.parquet",
  "entity_type": "wavelength_spectrum",
  "data_kind": "data_arrays"
}

The signal data is encoded using either point layout or chunked layout. The entity index column MUST be named wavelength_spectrum_index, and a co-located time column, if written, SHOULD be named wavelength_spectrum_time. The main wavelength-axis array SHOULD be named wavelength and the intensity array intensity, mirroring the mz/intensity convention for mass spectra; as elsewhere, readers resolve signal columns through the array index rather than by name.

When using null marking, follow the null semantics for signal data carefully for profile data.

28.2 Wavelength spectrum metadata — wavelength_spectra_metadata.parquet

{
  "name": "wavelength_spectra_metadata.parquet",
  "entity_type": "wavelength_spectrum",
  "data_kind": "metadata"
}

This table uses the metadata table layout. It mirrors the spectrum metadata schema.

28.3 Wavelength spectrum scan metadata — wavelength_spectra_metadata_scans.parquet

{
  "name": "wavelength_spectra_metadata_scans.parquet",
  "entity_type": "wavelength_spectrum",
  "data_kind": "scans"
}

This table uses the metadata table schema.

A scan or acquisition from the original raw file used to create a spectrum.