Scientific InstrumentValidated with real files

Galactic/Thermo GRAMS Spectrum (.spc)

.spc

Galactic Industries / Thermo Scientific GRAMS spectroscopy software, and instrument software built on the same SPC format

What it is

A binary spectroscopy file format from Galactic Industries (later Thermo Scientific)'s GRAMS software — one of the most common single-spectrum export formats from FTIR, Raman, and UV-Vis instrument software from the mid-1990s onward.

Who produces it

Spectroscopy labs running instrument software that exports via the GRAMS SPC format — common across FTIR, Raman, and UV-Vis instruments.

What we read / what we don't read

What we read

  • "New format" SPC files (fversn byte 0x4B) — essentially all files produced since the mid-1990s
  • Single-subfile spectra (one spectrum per file)
  • Y data as IEEE float32, OR as integer-scaled values (a common encoding in real 1990s-2000s instrument software — the scaling formula was verified against a real reference implementation and against real GRAMS/Thermo test files)
  • X values, either evenly spaced (reconstructed from the file's first/last-point range) or an explicit stored array

What we don't read

  • The older pre-1996 SPC header layout — rejected with a clear error, not silently misread
  • Multi-subfile (TMULTI) files carrying a Z-axis series of spectra
  • The TXYXYS per-subfile embedded-X layout — rejected explicitly rather than misread as the simpler TXVALS layout
  • The 16-bit (TSPREC) integer-word variant's formula is reference-verified but has no real test file confirming it yet — treat that specific narrow case with extra caution

How to import it into AltaiPlot

  1. Open AltaiPlot and drag your .spc file onto the window, or use File → Import.
  2. AltaiPlot detects the SPC binary signature and reads it directly — no external dependency involved.
  3. The spectrum lands as a plotting-ready X/Y column pair.
  4. Older pre-1996 files, multi-subfile files, or TXYXYS-layout files are rejected with an explicit error rather than misread.

Related formats

JCAMP-DX Spectroscopy (.jdx/.dx).jdx, .dx, .jcm

Auditability note: this page's capability claims are sourced fromsrc/renderer/src/engine/v7/import/importers/SpcImporter.ts:36 — see the full format list for every extension AltaiPlot recognizes.