Knowledge Bank

On condensing the products of an ethane plus krypton discharge (the krypton being in excess by a factor of 30) on a liquid helium cooled quartz tube three sharp lines near 2600 A were observed in absorption through the deposit. The spectrum showed an isotope shift with ethane-$de$, the vibrational spacing going from $900\pm 50cm-1$ to $725\pm 50cm-1$ for the fully deuterated ethane, With ethane 1,2 $d2$ at least one new set of bands was present. On the basis of the isotope shifts and the fact that there are no known molecules which could be formed from an ethane discharge which exhibit similar absorption it was postulated that the observed species was $CH2$. That the spectrum is due to $CH2$ was substantially verified since it was found that the photolysis products of both $CH2CO$ and $CH2N2$ in krypton yield the same spectrum as that from the ethane discharge. At this time it is impossible to state whether ground state of $CH2$ is $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}A1$ or $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}B1$ and very little can be said about the molecular geometry. At least one of the states involved in the transition is bent since the $900cm-1$ spacing probably corresponds to the $\nu 21$ bending mode, which is expected to appear strongly when there is a difference in angle between the two states.