Monofluorinated polycyclic aromatic hydrocarbons in Shpol'skii spectroscopy

The basic requirement to achieve high resolution in Shpol'skii spectroscopy is that the guest molecules fit well in the crystalline host alkane matrix , a condition that is usually met by polycyclic aromatic hydrocarbons (PAHs ). Despite the electronegativity of the fluorine atom, which might be thoug ht to strongly reduce the compatibility of guest and host, high-quality spe ctra can be recorded also for monofluorinated polycyclic aromatic hydrocarb ons (F-PAHs), as was shown for seven test analytes, viz. 1-fluoronaphthalen e, 1-fluorophenanthrene, 3-fluorochrysene, 1-fluoropyrene, 2-fluorofluorene , 3-fluorofluoranthene and 9-flurobenzo[k]fluoranthene. Lamp-excited spectr a were recorded in order to facilitate simultaneous excitation of PAHs and F-PAHs. The intensities and spectral qualities of the F-PAHs are similar to those of the parent compounds, but the Oa transitions are shifted from 0.5 to 7.3 nm in the fluorescence mode; that is, the spectra do not overlap. F or a number of F-PAHs, both the fluorescence and the phosphorescence transi tions can be utilized. (C) 2001 Elsevier Science B.V. All rights reserved.