Raman and fluorescence spectra of size-selected, matrix-isolated C14 and C18 neutral carbon clusters

The surface plasmon polariton-enhanced Raman spectra of size-selected, matrix-isolated C14 neutral clusters are presented along with the calculated vibrational frequencies for the ring and linear chain isomers. The Raman spectra show resonance enhancement over a range of excitation wavelengths from 457.9 to 514.5 nm. The measured vibrational spectra are most consistent with the linear chain isomer. In addition, the first fluorescence spectra of neutral, mass-selected Cn (14, 18) clusters are presented. The isolated C14 clusters display strong fluorescence and vibronic structure between 520 and 700 nm. The origins of the observed fluorescence for both C14 and C18 (previously reported) are investigated using the ZINDO/S, CIS and TD-B3LYP methods.