2-Photon Absorption And 3Rd-Harmonic Generation Of Di-Alkyl-Amino-Nitro-Stilbene (Dans) - A Joint Experimental And Theoretical-Study

The one- and two-photon optical absorption spectra as well as the frequency dependent third-harmonic generation response of a side-chain polymer containing 4-dialkylamino-4\u27-nitro-stilbene (DANS) as its side group have been measured over a wide range of frequency. A three-state model, based on an intermediate neglect of differential overlap/multireference double-configuration interaction description of the excited states, provides a coherent picture of the dynamic response of DANS, but fails in reproducing the red shift observed when going from the linear to the nonlinear absorption spectra; including vibronic coupling within the Franck-Condon approximation improves the fit

Near-infrared luminescence of Yb3+, Nd3+, and Er3+ azatriphenylene complexes

Near-infrared luminescent ytterbium(III), neodymium(III), and erbium(III) complexes containing novel organic chromophores derived from azatriphenylene have been prepared and spectroscopically studied. The complexes can be excited from 350 to 450 nm, leading after intramolecular energy transfer to intense lanthanide luminescence in acetonitrile. Quenching of the luminescence of the complexes by molecular oxygen reveals information on the rate of energy transfer from the “antenna” to the lanthanide ion

Trace analysis of 3-hydroxy benzo[a]pyrene in urine for the biomonitoring of human exposure to polycyclic aromatic hydrocarbons

Determination of benzo[a]pyrene (BaP) metabolites in urine can provide direct insight into recent exposure to BaP integrated from all uptake routes. In order to detect 3-OH BaP in human urine after exposure to BaP at the workplace, extremely sensitive methods need to be developed. In this paper, a new extraction method is presented, and two laserbased fluorescence techniques are evaluated. Using HPLC with laser-induced fluorescence detection, a detection limit of 8 ng/L was obtained. With laser-excited Shpol'skii spectrometry after chemical derivatization, 3-OH BaP could be detected at even a 0.5-ng/L concentration. In a pilot study, urine samples from coke-oven workers and from occupationally nonexposed control persons were analyzed. In the control samples, the average 3-OH BaP concentration was 8.3 ng/L; the 3-OH BaP concentrations were found to be highly correlated (r2 = 0.89) with urinary 1-OH pyrene, a widely used biomarker for polycyclic aromatic hydrocarbon (PAH) exposure. Significantly elevated 1-OH pyrene concentrations were measured in urine samples from coke-oven workers, but in most samples a corresponding increase of 3-OH BaP was not observed. Possible explanations for this discrepancy are discussed