Combination bands of small linear carbon clusters: an infrared isotopic study

Isotopically labeled linear carbon clusters C-n (n = 5,6,7,9) have been pro duced by pulsed laser ablation of mixed (C-12/C-13) carbon pellets, deposit ed in Ar matrices at 12 K and studied by Fourier transform infrared spectro scopy in the v > 2200 cm(-1) energy region. The resulting spectra were comp ared with computed isotopomer frequencies using DFT/B3LYP/cc-pVDZ level cal culations. Combination bands of C-12/13(n) linear clusters are assigned and used to extract the frequencies of the fundamental symmetric mode vibratio ns of these clusters in their electronic ground states. (C) 2000 Elsevier S cience B.V. All rights reserved.