Knowledge Bank

To characterize vibrational energy relaxation, this $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}B2(\pi ,\pi \ast )\leftarrow 1A1$ transition of the p-alkylaniline series has been studied in a supersonic free jet. The two quanta $NH2$ inversion mode in these molecules is expected to be weakly coupled to the low frequency torsion and bends of the para-subtituted alkyl chain. The absorption spectra of the series aniline through p-butylaniline show that the inversion mode is largely unaffected by the length of the alkyl chain. Even for such weakly coupled modes, the fluorescence spectra from the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}B2$ state shows vibrational relaxation occurring into the chain modes within a nanosecond.