Show simple item record

dc.creatorSpringer, M. G.en_US
dc.creatorJagusch, S. P.en_US
dc.creatorHlavacek, N. C.en_US
dc.creatorDrucker, S.en_US
dc.date.accessioned2008-07-15T13:27:12Z
dc.date.available2008-07-15T13:27:12Z
dc.date.issued2008en_US
dc.identifier2008-TG-08en_US
dc.identifier.urihttp://hdl.handle.net/1811/33246
dc.descriptionR. A. Back and R. D. Gordon, J. Molec. Spectrosc.en_US
dc.descriptionAuthor Institution: Department of Chemistry, University of Wisconsin-Eau Claire; Eau Claire, WI 54702en_US
dc.description.abstractThe cavity ringdown absorption spectrum of 4-cyclopenten-1,3-dione (CPD) was recorded near 487 nm in a room-temperature gas cell. The very weak band system ($\epsilon < $ 0.05 dm$^3$ mol$^{-1}$ ${\rm cm}^{-1}$) in this region is due to the $T_1(n, \pi$*$) \leftarrow S_0$ electronic transition. The origin band was observed at \mbox{20,541$\pm 1$ ${\rm cm}^{-1}$}. We have assigned 15 vibronic transitions in a region extending to about \mbox{$+700$ ${\rm cm}^{-1}$} relative to the origin band. From these tentative assignments we determined fundamental frequencies for several vibrational modes in the $T_1$ excited state. These include the out-of-plane ring modes $\nu_{19}'$ ($b_1$) and $\nu_{14}'$ ($a_2$). The table below compares their frequencies to corresponding values} {\bf 204}, 85 (2000).} in the $S_0$ electronic ground state and the $S_1(n, \pi$*$)$ excited state. \begin{center} Ring frequencies (cm$^{-1}$) of CPD in its lowest electronic states \vspace{-.2in} \end{center} \begin{displaymath} \begin{array}{ccccc}\hline \rule[0mm]{0mm}{3mm} {\rm Mode} & {\rm Description} & S_0 & S_1 & T_1 \\ \hline \rule[0mm]{0mm}{3mm} \nu_{19} & {\rm pucker} & 99 & 160 & 106 \\ \nu_{14} & {\rm twist} & 239 & 307 & 299 \\ \hline \end{array} \end{displaymath} The increases in these ring frequencies upon electronic excitation signify that the nominal $n \rightarrow \pi^*$ chromophore is delocalized to include the conjugated ring atoms. It is noteworthy, though, that the $\nu_{19}$ fundamental increases by only 7 cm$^{-1}$ upon $T_1 \leftarrow S_0$ excitation, compared to 61 cm$^{-1}$ for the $S_1$ excitation. Other cyclic conjugated enones show differences ($S_1$ vs.\ $T_1$ ring frequencies) of similar magnitude. These findings are attributable to the configuration mixing that each of the excited states undergoes. The two $n,\pi^{*}$ excited states may undergo mixing within distinctly different manifolds of spin-orbitals.en_US
dc.language.isoEnglishen_US
dc.publisherOhio State Universityen_US
dc.titleCAVITY RINGDOWN ABSORPTION SPECTRUM OF THE $T_1 (n,\pi^{*}) \leftarrow S_0$ TRANSITION OF 4-CYCLOPENTEN-1,3-DIONEen_US
dc.typeArticleen_US


Files in this item

Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail
Thumbnail

Items in Knowledge Bank are protected by copyright, with all rights reserved, unless otherwise indicated.

This item appears in the following Collection(s)

Show simple item record