Knowledge Bank

The photodetachment threshold spectra for small carbon cluster anions $Cn$-($n=3.9$) have been obtained using a tunable pulsed dye laser. The $Cn$- ions were produced by laser vaporization, and were mass selected, trapped and detected in an ICR spectrometer. Our result of the measurement of the electron affinities is in agreement with that from photoelectron measurement by Smalley $etal1$. Based on the Wigner law, the threshold behaviour of the cross sections for the odd-numbered spices can be interpreted by assuming a linear cumulene structure for the molecular anions while it appears that the data for even-numbered spices cannot be easily interpreted.