Raw FTIR transmission spectra of methanol isotopologues in pure and mixed ice analogues

This dataset contains unprocessed Bruker OPUS exports of FTIR transmission measurements of pure methanol isotopologue ices, binary mixtures of methanol and d-methanol, and ternary mixtures of H₂O:methanol:d-methanol and CO:methanol:d-methanol. Spectra were acquired at 10 K and after annealing to 120 K. The included isotopologues are CH₃OD, CH₂DOH, CHD₂OH, CD₃OH, and CD₃OD. All files are provided exactly as exported from OPUS. No baseline correction, smoothing, normalization, conversion to absorbance, or atmospheric or background correction has been applied. Exports include the full set of OPUS output files, such as interferograms, reference spectra, ratio spectra, and transmission spectra. Folder structure: top-level folders are organised by ice composition and temperature. Subfolders contain datasets corresponding to different mixing ratios. Instrument and acquisition parameters (Bruker Vertex 70v, OPUS 8.7.31): measurement mode FTIR transmission. Measurement channel sample compartment. Source MIR. Beamsplitter Wide Range MIR–FIR. Detector RT-DLaTGS Wide Range in internal position 1. Aperture 8 mm. ATR pressure 0. High-pass filter open. Low-pass filter 5 kHz. Variable low-pass filter 4000 cm⁻¹. Optical filter open. Scanner velocity 5 kHz. External synchronisation off. FT processing parameters as exported by OPUS: apodization Blackman–Harris (3-term). Phase correction Mertz. Phase resolution 8 cm⁻¹. Stored phase mode no. Zero filling factor 2. Frequency limits 6000–30 cm⁻¹. Non-linearity correction 0. Contact: Adam Vyjidak, Max-Planck-Institut für extraterrestrische Physik, [e-mail] License: CC-BY 4.0