Knowledge Bank

The wide spectral coverage and high sensitivity of Mode-Locked Cavity Enhanced Absorption Spectroscopy (ML-CEAS) are illustrated by the observation of a very high overtone transition of $C2H2$ in the blue spectral region (420 nm, 8 quanta of CH stretch excitation), which was easily accessed by frequency-doubling a modelocked femtosecond Ti:Sapphire laser. The detection limit is about $10-8/cm$. The rotational analysis of this $\Sigma u+-\Sigma g+$ parallel band, centred at $23813.244cm-1$, is presented and the vibrational assignment is discussed. T.Gherman, S. Kassi, A. Campargue, D. Romanini Chem. Phys. Lett. 383, 353-358 (2004)