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dc.creatorHudson, Bruce S.en_US
dc.creatorChristensen, R. L.en_US
dc.creatorKohler, Bryan E.en_US
dc.date.accessioned2006-06-15T13:20:40Z
dc.date.available2006-06-15T13:20:40Z
dc.date.issued1970en_US
dc.identifier1970-P-6en_US
dc.identifier.urihttp://hdl.handle.net/1811/8501
dc.descriptionAuthor Institution: Department of Chemistry, Harvard Universityen_US
dc.description.abstractPhotoselected emission studies of rigid glasses indicate that the lowest excited singlet state of all-trans retinal and all-trans retinoic acid is the $\pi-\pi^{*}$ state. This is in contrast to the situation in unsaturated aldehydes and ketones containing only one or two carbon-carbon double bonds where intensity and solvent shift data indicate a lowest n-$\pi^{*}$ singlet state. Absorption studies of crystals of retinoic acid reveal a low intensity shoulder at about 4650 \AA, an inflection at about 4350 {\AA} and a maximum absorption at about 3640 \AA. Since the lowest state is the $\pi-\pi^{*}$, this shoulder must be part of the $\pi-\pi^{*}$ transition, probably the strongly Franck-Condon fobidden 0--0 transition. This conclusion is supported by polarized absorption, polarized excitation and crystal fluorescence studies of the triclinic form of retinoic acid whose crystal and molecular structure are known. A reinvestigation of the spectrum of diphenyl-octatetraene reveals a clearly resolved, low intensity peak at 4320 \AA, a position corresponding closely to the vibrational spacing of the previously reported intense bands. The ratio of the extinction coefficients of the weak (0--0) band to the first intense band (0--1) is about 1/30. These experiments demonstrate that the lowest excited state of these polyenes is a $\pi-\pi^{*}$ state with a strongly Franck-Condon forbidden 0--0 transition suggesting significant rearrangement in the excited state. The ground state and excited state vibrational frequencies will be compared and the origin of the diffuse nature of the transition in the retinyl series will be discussed.en_US
dc.format.extent143306 bytes
dc.format.mimetypeimage/jpeg
dc.language.isoEnglishen_US
dc.publisherOhio State Universityen_US
dc.titleRETINYL AND DIPHENYL POLYENES. ABSORPTION AND PHOTO-SELECTED FLUORESCENCE STUDIES OF THE LOWEST SINGLET-SINGLET TRANSITIONen_US
dc.typearticleen_US


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