Convert Thermo OMNIC .spa files to CSV (Beta)

Thermo Scientific OMNIC, the software on Nicolet FTIR and Raman spectrometers, saves single spectra as .spa and spectrum groups as .spg. Both are binary files that only OMNIC opens. This page turns them into CSV so you can work with the data in Excel, Origin, R or Python, without OMNIC installed.

How to convert SPA to CSV

1. Upload one or more .spa files, an .spg group, or a ZIP of a folder.
2. Pick the number format: the default writes decimal points and commas between columns; the 1234,5 option writes decimal commas and semicolons, as German or French Excel expects.
3. Optionally, under More options, convert %T to absorbance or wavenumber to wavelength.
4. Download the CSV. The first line names axis and units, for example Wavenumber (cm-1),Transmittance (%).

What is in the CSV

• A single .spa gives two columns: x and the spectrum in the units OMNIC saved it in: %T, absorbance, %R, Kubelka-Munk, log(1/R), single beam or Raman intensity.
• An .spg group gives one column per spectrum, headed with the spectrum's title from OMNIC, for example Before dBAX 0.05 mg ml or an automatic Subtraction Result name.
• Several .spa files uploaded together are combined the same way. If their ranges differ, each spectrum gets its own x/y column pair.
• Groups or batches with more than 100 spectra switch to one spectrum per row, which keeps the table inside spreadsheet limits. You can force either layout under More options.

The collection details OMNIC stores (title, time, scans, resolution, laser frequency, range) appear in the preview and on the Excel file's metadata sheet.

Accuracy

Values were compared with an independent open-source OMNIC reader on nine real files, and with OMNIC's own CSV export for two of them. They match to the export's precision of about seven significant digits; this CSV keeps the file's full precision. Files from a French-language OMNIC read the same way.

Files that don't convert (yet)

• .srs series from rapid-scan, TGA-IR or GC-IR experiments are recognised but not supported. Export the spectra you need from OMNIC as .spa or as an .spg group.
• Interferogram-only files: an .spa that holds only raw interferograms and no processed spectrum is reported as such. Save the processed spectrum in OMNIC and upload that. Files that store an interferogram as their spectrum convert, with data point numbers as x.

For a formatted workbook with a chart, see OMNIC SPA to Excel.

More about what this tool reads and writes: Spectrum File Converter (OPUS, OMNIC, SPC, WDF, SP, JWS).