Knowledge Bank

The distribution of intensity in the perpendicular bands of allene has been examined, taking into account the effect of the Coriolis interaction between the degenerate levels $\nu 2$ and $\nu 10$. The results indicate that in all the perpendicular bands of allene and allene-$d4$ the branch lies on a line which divides the band into two equal (or very nearly equal) areas. This has been used as a criterion for a new rotational assignment of these bands and the rotational constants A and $\zeta$ have been re-evaluated. The present A values, together with $Stoicheff\prime s1$ B values indicate that the CH bond length is 1.061 A and the HCH angle $116\circ$.