Absorption and circular dichroism spectra of the c i s - and t r a n s -butadiene chromophores α- and β-phellandrene
1978; American Institute of Physics; Volume: 68; Issue: 6 Linguagem: Inglês
10.1063/1.436098
ISSN1520-9032
Autores Tópico(s)Molecular spectroscopy and chirality
ResumoThe absorption and circular dichroism spectra of gas-phase (−) -α-phellandrene and (−) -β-phellandrene have been measured in the spectral region 300–135 nm. Solution spectra of these compounds were measured in perfluoro-n-hexane to 160 nm. The spectra were interpreted in terms of the excited electronic states of the cis- and trans-butadiene chromophores. The overlapping valence and Rydberg states were unambiguously differentiated by comparison of the vapor and solution phase spectra. Comparison between absorption and CD spectra made possible the symmetry assignments of magnetic dipole allowed (as opposed to electric dipole allowed) excited states of butadiene. For both molecular systems the first observed excited singlet state corresponds to 1Bu for the trans chromophore and to 1B2 for the cis chromophore. No evidence was found for a ’’lowest-lying’’ singlet state of Ag or A1 symmetry.
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