Dipole Moment of the First Excited π* ← π State of Styrene

The Stark effect is observed in the rotational fine structure of the 0–0 band of the lowest lying $\mathrm{\pi *\hspace{0.17em}\leftarrow \hspace{0.17em}\pi }$ transition of styrene. This resulted in a $\text{|\hspace{0.17em}Δμ\hspace{0.17em}|\hspace{0.17em}=\hspace{0.17em}0.13}\mathrm{D}$ from the ground state. It is shown that the smallness of the change in dipole moment is consistent with the $\mathrm{\pi *\hspace{0.17em}\leftarrow \hspace{0.17em}\pi }$ transitions in similar substituted benzenes studied in this laboratory.