Structures and Energetics of Clusters and Macromolecules
Final rept. 1 Mar 1999-30 Nov 2002
CALIFORNIA UNIV SANTA BARBARA DEPT OF CHEMICAL AND NUCLEAR ENGINEERING
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Virtually all of the progress and accomplishments have been described in detail in previous annual progress reports. These will not be repeated here. Only those few new results initiated in the last few months of the grant will be listed. POSS Systems In the annual report submitted in September, 2002, we showed mass spectra of the StyxEpyT8 system synthesized at Edwards AFB, where x y 8, Sty stands for styrene and Ep for styrene with the vinyl group epoxidated. The pure Sty8T8 system had been discussed in previous reports and the work has recently been written up for publication. We showed preliminary arrival time distributions and averaged cross sections for Sty7EpT8 and Sty6Ep2T8 in the September, 2002, progress report. Since then we have also been able to obtain ATDs for the Sty5Ep3T8 species and have taken all 3 systems to 110 K to improve resolution. In each case we can resolve 3 isomers in the ATDs. Examples are given in Fig. 1 for Sty7EpT8 and Sty6Ep2T8. In Sty7EpT8 the isomers occur due to pairing of the non epoxided styryl capping groups 0 pairs, 1 pairs while in Sty6Ep2T8 and Sty5Ep3T8 the isomers are due to different arrangements of the Ep capping groups on the T8 cage. The 3 possibilities for the Sty6Ep2T8 system were shown in the September, 2002 progress report. In Fig. 2 we show the 3 possibilities for the Sty5Ep3T8 system, the experimental cross sections and the cross sections from our theoretical modeling. Sty-Sty pairs are shown in blue. Clearly the agreement is excellent giving confidence in the results. It is interesting that Sty-Sty pairing is only observed in cases where there is no epoxide adjacent to the styryl capping agent.
- Organic Chemistry
- Polymer Chemistry
- Atomic and Molecular Physics and Spectroscopy