High resolution infrared spectroscopy of the asymmetric C-H stretch of 1,2,4,5-tetracyanobenzene (TCNB) and (TCNB)(2) in superfluid helium nanodroplets.

We report the observation of the C-H stretch vibration of 1,2,4,5-tetracyanobenzene (TCNB) and (TCNB)(2) embedded in superfluid helium droplets. The asymmetric C-H stretch of TCNB was observed at 3053.488(3) cm(-1). The corresponding band of the (TCNB)(2) is slightly blueshifted and was observed at 3054.651(2) cm(-1). The intensity of the IR band is increased compared to the monomer absorption. Based on a comparison of our experimental results with predicted IR bands, we conclude that (TCNB)(2) is formed in a C(2h) structure in the droplet.