Electronic states of 1,4-bis(phenylethynyl)benzene: A synchrotron radiation linear dichroism investigation |
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Authors: | Duy Duc Nguyen,Nykola C. JonesSø ren V. Hoffmann,Signe H. AndersenPeter W. Thulstrup,Jens Spanget-Larsen |
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Affiliation: | a Department of Science, Systems and Models, Roskilde University, Universitetsvej 1, DK-4000 Roskilde, Denmark b Institute for Storage Ring Facilities, ISA, Aarhus University, Ny Munkegade, Bldg. 1520, DK-8000 Aarhus C, Denmark c Department of Basic Science and Environment, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark |
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Abstract: | The electronic transitions of 1,4-bis(phenylethynyl)benzene (BPEB) were investigated by UV synchrotron radiation linear dichroism (SRLD) spectroscopy in the range 25,000-58,000 cm−1 (400-170 nm) on molecular samples aligned in stretched polyethylene. The investigation was supported by variable temperature spectroscopy and by quantum chemical calculations in the LCOAO and TD-DFT models. The molecular alignment of BPEB in stretched polyethylene was found to be remarkably efficient, leading to an orientation factor equal to 0.95 for the long molecular axis. The observed band shape depended strongly on the degree of stretching and on temperature. The combined experimental and theoretical evidence leads to the characterization of several previously unobserved transitions and supports the assumption that BPEB adopts a nearly planar conformation in stretched polyethylene. |
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Keywords: | Oligo-p-phenyleneethynylenes (oPPE) Synchrotron radiation Linear dichroism UV absorption Electronic transitions Polarization |
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