Knowledge Bank

We have obtained highly resolved optical spectra of 2,12-dimethyl-tridecahexaene $((CH3)2-C=CH(CC=CH)4CCH3=CH2)$ in n-alkane hosts at $4.2\circ K$, A tunable dye laser System has been used to select single, well-defined sites in the host crystals. Excitation and fluorescence spectra of these sites show that the dominant C=C stretching frequency increases from $1576cm-1$ in the ground electronic state ($\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}Ag$) to $1773cm-1$ in the lowest excited state ($\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}Ag$). The implications of these results toward an understanding of the structure of the lowest excited electronic state will be discussed.