Photoelectric Properties and Detection of the Aromatic Carcinogens Benzo[a]pyrene and Dimethylbenzanthracene

• Published in: Proceedings of the National Academy of Sciences - PNAS 1979-09, Vol.76 (9), p.4180-4184
• Main Authors: Houle, William A., Brown, Hugh M., Griffith, O. Hayes
• Format: Article
• Language: English
• Subjects: Beam currents; Carcinogens; Electrons; Lipids; Microscopes; Molecules; P branes; Photoelectron spectroscopy; Photoelectrons; Wavelengths
• ISSN: 0027-8424
• DOI: 10.1073/pnas.76.9.4180

The absolute photoelectron quantum yield spectra for benzo[a]pyrene and dimethylbenzanthracene are presented in the wavelength range 180-230 nm. These polycyclic aromatic carcinogens have photoelectron quantum yields of approximately 2 × 10-3electrons per incident photon at 180 nm. The quantum yields fall off quickly and monotonically at wavelengths longer than 210 nm (5.9 eV). Threshold values for benzo[a]pyrene and dimethylbenzanthracene are 5.25 ± 0.06 eV and 5.27 ± 0.04 eV, respectively. The photoelectron quantum yields of benzo[a]pyrene and dimethylbenzanthracene are several orders of magnitude greater than typical components of biological membranes (amino acids, phospholipids, and polysaccharides). Preliminary micrographs of benzo[a]pyrene and dimethylbenzanthracene sublimed onto poly(L-lysine) and onto dimyristoyl phosphatidylcholine demonstrate the high contrast of small crystallites of carcinogens against a background of membrane components. These results and calculations involving relative contrast factors suggest that the distribution of these carcinogens in biological membranes can be determined by using photoelectron microscopy.