Infrared spectrum of the CO2–HCl complex in solid argon at 12 K

Co-condensation of CO2 and HCl in excess argon at 12 K produced the CO2–HCl hydrogen-bonded complex. Small shifts in the νs and ν3c modes, the low νl fundamental, and a very weak infrared Fermi doublet indicate a weakly bound complex. The more strongly bound CO2–HF and C 18O2–HF complexes gave more intense infrared Fermi doublets. The infrared intensity ratio ν3/ν1 is 200/1 for the CO2–HF complex demonstrating that the HF ligand induces finite electrical asymmetry in the CO2 submolecule.