Fig. 3: Details of the asymmetric CE channel induced by the electron recollision induced excitation.
a, b Measured θcm and KER distributions (Exp.) for region III. The dotted red and solid blue lines represent the fit and simulated results (sim.), respectively. c Detailed mechanism of the TERCE from the C state. The tunnelling electron is promoted to the ground state of the cation via tunnelling ionisation, and this ionised electron can recollide with the cation and excite a second electron to a higher excited state (C), which is also known as recollision induced excitation (RIE) (indicated as black arrow). This excitation initiates the large amplitude bending and asymmetric stretching motions. This enables the molecule to relax to the minimum of the PES of the C state, where further tunnelling ionisation to the dication state occurs instantly because of the much lower ionisation potential at larger bond lengths. The wave-packets evolve along the dication for certain time interval and are projected to the trication via enhanced ionisation. Finally, the wave-packet dissociates along the quartet state of the trication.
