Download
slide1 n.
Skip this Video
Loading SlideShow in 5 Seconds..
References PowerPoint Presentation

References

132 Vues Download Presentation
Télécharger la présentation

References

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Vibrational spectroscopy of C60 photopolymer Funding: OTKA T034198, OTKA T032613, NATO PST.CLG.977404 G. Klupp*, K. Kamarás, É. Kováts, S. Pekker, T. Pusztai Research Institute for Solid State Physics and Optics,P. O. Box 49, Budapest, H 1525, Hungary, *email: klupp@szfki.hu Z.-T. Zhu†, V. C. Long‡, J. L. Musfeldt§ Department of Chemistry, State University of New York at Binghamton, Binghamton, New York 13902 G. B. Adams, J. B. Page Department of Physics and Astronomy, Arizona State University, Tempe, Arizona 85287 Introduction Monomer + Dimer + Trimers (5 possible structures) + Tetramers (17 possible structures) + Higher oligomers (insolubes) Photopolymer = [1], [2], [3] … a = 13.93 – 14.05 Å  average ~2 cycloadditional bonds / C60 unit [2], [4] Different preparation conditions  different ratio of the compounds [3], [5] Measured Ag(2) modes Preparation Calculations Measurements • Illumination of C60 + saturated C60 solution with 2*23W at 320-360K for 40 days  C60 + (C60)2 + soluble (C60)n>2 + insoluble (C60)n>2 • Repeated extraction with toluene  solid photopolymer with less C60, (C60)2  solution of C60 + (C60)2 • HPLC separation of the solution (C60)2, 99.3% purity • For the preparation of trimer see poster of É. Kováts • Method: • QMD (quantum molecular dynamics) [6] • local pseudoatomic orbitals, minimal basis • best results: 200-600 cm-1 (FarIR): with 1.05 uniform scaling 2% error • intensities not reliable • Molecules: • triangle: most possible (C60)3 • rectangle: most possible (C60)4 • Raman: Renishaw System 1000B microscope • + 785nm laser  further polymerization avoided • MIR: KBr pellet in Bruker IFS28 • FIR: pure photopolymer pellet @ LHe (4 K) in Bruker IFS 113v • Weak lines seen sharper lines 5 cm-1/ cycloadditional bond Photopolymer contains: C60 + (C60)2 + (C60)3 + higher oligomers Measured and calculated MidIR spectra Measured and calculated FarIR spectra calc. rectangle calc. triangle exp. photopolymer exp. dimer Photopolymer contains dimer, but other oligomers are present MidIR: assignment of oligomer peaks not conclusive  FarIR: fewer lines + no C60 lines No interball modes 30-200 cm-1 Assignment of photopolymer spectrum with dimer, triangle and rectangle Unassigned peaks: insoluble oligomers + small amount of other trimers and tetramers Conclusions • Ag(2): 5 cm-1/ cycloadditional bond • No interball modes in IR 30-200 cm-1 • FarIR more informative for assignment than MidIR • Photopolymer contains monomer + dimer + triangle + rectangle + other oligomers References [1] A. M. Rao, P. Zhou, K-A. Wang, G. T. Hager, J. M. Holden, Y. Wang, W-T. Lee, X-X. Bi, P. C. Eklund, D. S. Cornett, M. A. Duncan, I. J. Amster, Science 259, 955 (1993) [2] T. Pusztai, G. Oszlányi, G. Faigel, K. Kamarás, L. Gránásy, S. Pekker, Solid State Commun. 111, 595 (1999) [3] S. Pekker, K. Kamarás, É. Kováts, T. Pusztai, G. Oszlányi, Synthetic Metals 121, 1109 (2001) [4] S. Pekker, É. Kováts, K. Kamarás, T. Pusztai, G. Oszlányi, Synthetic Metals 133-134, 685 (2001) [5] B. Burger, J. Winter, H. Kuzmany, Z. Phys B 101, 227 (1996) [6] O. F. Sankey, D. J. Niklewski, Phys. Rev. B 40, 3979 (1989) Present addresses: † Department of Material Science and Engineering, Cornell University, Ithaca, NY 14853 ‡ Department of Physics and Astronomy, Colby College, Waterville, ME 04901 § Department of Chemistry, University of Tennessee, Knoxville, TN 37996