Knowledge Bank

According to the commonly accepted $Vh$ symmetry of the $N2O4$ molecule and the X-ray crystal structure of Broadley and $Robertson2$, present $theory3$ predicts one infrared active component in the crystal for each infrared active fundamental of the gaseous molecule. These components, with one exception, have been observed in polycrystalline films of $N2O4$ at liquid air temperature as sharp bands only slightly shifted from the gas frequencies. The $684cm-1$ fundamental is apparently too weak to be observed. Additional bands, associated with the fundamentals and some combinations, indicate at least two lattice modes in the frequency range 17 to $24cm-1$. The spectrum will be discussed along with that of solid $N2O4$ containing about 35 atom % of $N15$.