Revisiting Laser-Intensity-Dependent Ionization and Fragmentation of C60

We revisit the laser-intensity-dependent ionization and fragmentation yields of C-60 molecules irradiated by 25-fs, 798-nm laser pulses based on the approach in which photoions are measured via a velocity map imaging spectrometer working in a time-sliced mode. This approach dramatically improves the signal-to-background ratio compared to those using a simple (traditional) time-of-flight mode (spectrometer), and thus allows us to measure the laser-intensity dependences down to a previously untouched region, which is expected to provide new insights into the intense-field ionization and fragmentation of C-60. Indeed, we find that the saturation intensities for C-60 ionizations and the onset intensity for C-60 fragmentation are much lower than those reported in previous experiments. Furthermore, the derived saturation-intensity dependence on charge distribution demonstrates the validity of the over-the-barrier ionization using a conducting sphere model.

Automated summary

In this study, a new approach was used to investigate the laser-intensity-dependent ionization and fragmentation yields of C60 molecules. It was found that the saturation intensities for C60 ionizations and the onset intensity for C60 fragmentation are much lower than previously reported, confirming the validity of over-the-barrier ionization using a conducting sphere model.