Knowledge Bank

In the complex of pyrazine-hexafluoroisopropanol, the $000$ of the lowest $n\pi \ast$ transition is as sharp as that of the parent and is blue-shifted $408cm-1$, with lifetime shorter than 3 ns. This blue shift roughly gives the hydrogen bond energy in the $S1(nx\ast )$ of $2740cm-1$. Our interpretation to the short lifetime is that due to the large stabilization of the hydrogen bond, the $S1$ is below $T2(xx\ast )$. which breaks down the coupling between them, resulting in the quenching of the slow component of fluorescence