The collisional relaxation of the J=5←4 rotational transition of CO induced by carbon monoxide, nitrogen, and oxygen has been studied at room temperature. Pressure-broadening parameters were determined as 3.29(2), 2.61(2), and 2.30(2) MHz/Torr for CO, N2, and O2 buffer gases, respectively. Experimental deviations from the Voigt line shape profile have been observed which are mostly the effect of a narrowing in the spectral line core. The difference between the model profile and the experimental profile is less than 0.5% of the maximum line amplitude in the investigated pressure range 0.2–5 Torr. In addition, a small positive collision-induced shift of the line center frequency was observed for the pure gas, corresponding to a pressure self-shift parameter of 6(3) kHz/Torr.

The polymerization of glycolide in a melt containing SbF3 proceeds to 100% conversion in the temperature interval 160–175° and the number of active centres increases with time. The polymerization process features reactions of chain propagation and acyl ion binding by carbonyl groups of the monomer and polymer molecules, as normally occurs with lactones, but an additional feature of this process is the dissociation of ion pairs to free ions. The initial stages of polymerization involve relatively slow initiation with the participation of two initiator molecules. In the light of data on the viscosity of the polyglycolide in the melt the “living” character of the growing chain ends is postulated. A formula is derived which relates the viscosity of polyglycolide in the melt to number-average molecular mass.