Knowledge Bank

Remeasurement of the primary photodissociation quantum yield of Carbonly Sulfide by excitation into the absorption region from 300 nm to 200 nm gave values from .65 to .80 indicating that a larger portion of this absorption feature might be due to absorption into a discreet state rather than a dissociation continuum as heretofore assumed. Spectra were taken at $25\circ C$ and -$78\circ C$ in such a manner as to enhance the weak features noted by Brackenridge and $Taube1$. What were assumed to be vibration at lines with spacings of $710cm-1$ are shown to be composed of several vibrational bands showing different temperature dependencies. The absorption is assumed to be due to the transition $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta \leftarrow \Sigma +$ where the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta$ state is split into $A\prime$ and $A\prime \prime$ states by a nonlinear molecular configuration. The states badly perturb each other giving rise to the observed complex spectrum. A very weak series of bands with a spacing of $\sim 420cm-1$ was discovered on the red edge of the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta \leftarrow 1\Sigma +$ transition. These features are most likely due to the more highly forbidden $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma -\leftrightarrow 1\Sigma +$ transition and could also perturb the neighboring $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Delta \leftarrow 1\Sigma +$ transition adding to its complexity.