XANTHENE DYES—A MODIFIED PPP-CI TREATMENT

The absorption spectra of 3 typical xanthene dyes were measured. Their properties were computed by using a modified PPP—CI method and the standard parameters, It is shown that the calculated singlet transition energies are well consistent with the observed data. Many other calculated results are also presented. Furthermore, some calculated first excited properties are compared with the ground ones, and the differences between photochemical reactions occured in the excited state and the ground thermochemical ones are predicted.