Knowledge Bank

Spectral investigations of the structure of the high temperature phase of $C2H2$ and $C2D2$ are in agreement with the proposed $Th6$ space group with 4 molecules/unit cell on $S6$ sites. Raman and new infrared results on the low temperature phase provide support for a $D2h$ orthorhombic structure similar to those of the halogens and carbon disulfide, in which the molecular axis is not coincident with the figure axis of the site.