DIFFUSE INTERSTELLAR BANDS AND UV EXTINCTION CURVES - THE MISSING LINK

The connection between diffuse interstellar bands and components of th e interstellar ultraviolet extinction curve, decomposed according to t he Fitzpatrick & Massa scheme, is analysed from new observations of se veral DIBs in the line of sight to 28 stars measured by IUE. We find t hat the strength of the 217.5 nm bump positively correlates with DIB s trength, whereas correlations with a negative slope exist with the FUV non-linear rise and the width of the bump. There is no correlation wi th linear rise. The relation of bump height versus DIB strength does n ot pass through zero. The results are interpreted within the polycycli c aromatic hydrocarbon (PAH) framework. They strengthen the hypothesis that the FUV non-linear rise is produced by neutral PAHs, whereas DIB carriers are found among some ionised or radical PAHs.