THE ELECTRONIC STATES OF FURAN STUDIED BY VUV ABSORPTION, NEAR-THRESHOLD ELECTRON-ENERGY-LOSS SPECTROSCOPY AND AB-INITIO MULTIREFERENCE CONFIGURATION-INTERACTION CALCULATIONS

The results of large-scale ab initio CI calculations on the electronic states of furan, using a multi-reference multi-root CI method (MRD-CI ), are related to new VUV absorption and low-energy electron energy-lo ss (EEL) measurements, leading to detailed spectral assignments. All o f the expected 1,3pipi states have been assigned, there being improve d agreement between theoretical and experimental energies in all cases . A number of new Rydberg series has been identified by experiment and , for these also, the calculations perform well. In addition, cationic states and ground state molecular electronic properties have been com puted.