Knowledge Bank

In most SVL fluorescence experiments the excitation bandwidth is sufficiently broad to cover essentially the entire rotational contour of the vibronic level excited. As a result the observed contour in emission is generally quite similar to the absorption band contour and represents emission from a rotationally equilibrated vibronic level. By the use of narrow bandwidth excitation $(--0.2-0.8cm-1)$, however, a non-Boltzmann rotational distribution can be created in the excited state vibronic level which can be reflected in a change in the shape of the emission band contours. By monitoring the change in band contour as a function of pressure one can get a qualitative picture of the efficiency of rotational equilibration in the excited vibronic level. We wish to report here such experiments performed on the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}B2u$ zero-point Level in benzene excited by pumping the $B00(610)$ absorption band.