dc.creator Kliger, D. S. en_US dc.creator Albrecht, A. C. en_US dc.date.accessioned 2006-06-15T13:18:53Z dc.date.available 2006-06-15T13:18:53Z dc.date.issued 1970 en_US dc.identifier 1970-F-6 en_US dc.identifier.uri http://hdl.handle.net/1811/8415 dc.description Author Institution: Chemistry Department, Harvard University; Chemistry Department, Cornell University en_US dc.description.abstract Transitions originating from excited electronic states of anthracene, 2-methylanthracene and 9-methylanthracene are investigated. Using kinetic spectroscopic techniques with nanosecond time resolution, spectra are measured in both ethanol and lucite solutions. Polarizations of the absorptions in lucite samples are also measured. Anthracene shows its well-known long-lived transient absorption of the triplet state at 425 nm which is assigned to a $^{3} B_{1g}\leftarrow ^{3}B_{2u}$ transition. In addition, a transient absorption having a very strong oscillator strength is observed at 427 nm which decays in a few nanoseconds. This is assigned to a $^{1}A_{g}\leftarrow ^{1}B_{2u}$ transition out of the first excited singlet state of anthracene in excellent agreement with theoretical results. The methylanthracenes studied show triplet spectra almost identical to that observed in anthracene. However, the short-lived transient spectrum of anthracene changes dramatically upon methylation. In addition to the anthracene transition, now shifted to 405 nm, new strong transitions are observed at 420 and 435 nm. Their polarization tends to favor the direction of the methyl substituent. Isotope studies show that these new transitions do not originate from the first excited singlet state of the derivative. The evidence suggests that one may be seeing a transition out of an upper triplet state. The most appealing candidate is a low lying $\sigma-\sigma^{*}$ triplet state with a natural lifetime on the order of fractions of nanoseconds. en_US dc.format.extent 146781 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title POLARIZED SPECTROSCOPY OF EXCITED STATES OF SUBSTITUTED ANTHRACENES ON A NANOSECOND TIME SCALE en_US dc.type article en_US
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