The high resolution spectrum of the S-1 <- S-0 transition of anisole

The high resolution electronic excitation spectrum of the band origin in th e S-1<--S-0 electronic excitation of anisole has been measured in a molecul ar beam experiment. High accuracy upper state rotational constants have bee n determined from the fit of more than 400 rovibronic transitions (with a 1 0 MHZ standard deviation). The planarity of anisole in both the ground and the excited state has been clearly demonstrated and additional information gained about the changes in the structure with electronic excitation.