The Infrared spectrum of a molecular aggregate. The HCN dimer isolated in an argon matrix

Spectral properties of well-defined molecular aggregates are difficult to obtain. A study is presented which demonstrates that a well-defined molecular aggregate may be produced by photochemical methods. This is specifically shown by producing the HCN dimer from the photochemical decomposition of s-tetrazine. The infrared spectrum of the dimer clearly shows that the vibrational bands associated with the hydrogen bond are intensified and broadened in comparison to those not involved in the hydrogen bond.