Systematics in the IR Absorptions of Odd Carbon Chains 21 st of June 2005, Columbus Dmitry Strelnikov, Roman Reusch and Wolfgang Krätschmer Max-Planck-Institut für Kernphysik, Heidelberg, Germany

Experimental Setup

Matrix-isolated carbon molecules Carbon vapor molecules as deposited in cryogenic Ne-, Ar- or Kr-matrices Chain growth by matrix annealing UV/Vis-spectra before and after annealing in Ar IR-spectra before and after annealing in Ar

Strategy □Comparison of IR and UV/Vis absorptions of C n in Ar and O 2 matrices □Method´s test: Selective oxidation of C n with known IR and UV/Vis absorption spectra □Method´s application: Selective oxidation of C n with unknown IR but known UV/Vis absorptions □Looking for systematics in the IR spectra of long C 2n+1 molecules 

D.Forney, P.Freivogel, M.Grutter and J.P.Maier, J. Chem. Phys., 1996 C n absorbtions in Ar matrix, UV-vis spectrumC n absorbtions in Ar and O 2 matrices, UV-vis spectrum

A. Van Orden and R. Saykally; Chem. Rev C n absorbtions in Ar and O 2 matrices, IR spectrumC n absorbtions in O 2 matrix, IR spectrumC n absorbtions in Ar matrix, IR spectrum

Isotopic substitution of matrix oxygen. The way to distinguish pure carbon molecules and oxides.

□Comparison of IR and UV/Vis absorptions of C n in Ar and O 2 matrices □Method´s test: Selective oxidation of C n with known IR and UV/Vis absorption spectra □Method´s application: Selective oxidation of C n with unknown IR but known UV/Vis absorptions □Looking for systematics in the IR spectra of long C 2n+1 molecules  

Selective LASER-induced oxidation of carbon chains in O 2 - matrices. Difference in absorption before and after LASER exposure UV-vis IR

□Comparison of IR and UV/Vis absorptions of C n in Ar and O 2 matrices □Method´s test: Selective oxidation of C 9, C 11, C 13 having known IR and UV/Vis absorption spectra □Method´s application: Selective oxidation of C n with unknown IR but known UV/Vis absorptions □Looking for systematics in the IR spectra of long C 2n+1 molecules   

□Comparison of IR and UV/Vis absorptions of C n in Ar and O 2 matrices □Method´s test: Selective oxidation of C n with known IR and UV/Vis absorption spectra □Method´s application: Selective oxidation of C n with unknown IR but known UV/Vis absorptions □Looking for systematics in the IR spectra of long C 2n+1 molecules    

IR-absorptions of carbon molecules in Ar, 30K Where are the (3N-5)/2 IR-active modes ?

PM3, DFT(b3lyp/6-311G(d)) - intensity of the k-th vibrational mode  - dipole moment, x k, s k - Cartesian and normal coordinates, q i - Mulliken charges, L i,k – matrix of vibrational eigenvectors as columns ( ) Intensities of infrared absorptions of long odd-numbered carbon chain molecules

Red and blue Ne-to-Ar (gas-to-Ar) matrix- shifts of the totally alternating vibration for long odd-numbered carbon chains C n in gas phase * ** *- Prediction

Conclusion The method of selective laser-induced oxidation works and turned out to be useful for the characterization of odd linear carbon chains. A regularity in the IR-absorptions of linear C 2n+1 species was established.

Freivogel P., Grutter,M., Forney,D., Maier,J.P.; Chem.Phys. 1997

T.F. Giesen et al.; Science, 1994

1809 cm -1, gas phase T.F. Giesen et al.; Science, 1994

Crystal structures of solid oxygen <23.8K K K G.C. De Fotis, Phys. Rev. B, 1981

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