The ultrafast dynamics and dissociative ionization of CS2 were studied using the pump-probe method with time-of-flight mass spectroscopy. The transient behavior of both parent ion (CS2+) and fragment ions (S+ and CS+) was observed. It was found that all the ionic signals decay exponentially with lifetimes that were different for delay times, t>0 and t<0, which can be attributed to the evolution of different Rydberg states pumped by 267-nm and 400-nm laser pulses. The lifetimes of two Rydberg states were obtained simultaneously from one fitting of the transients. The fragment ions were produced by the dissociation of CS2+, and it is suggested that the final ionic state is the C2Σg+ state of CS2+ based on the measured S+/CS+ branching ratio. The S+/CS+ ratio is dependent on the delay time of the two lasers, indicating that the dissociation process of CS2+ is related to the evolution of the intermediate Rydberg state.
ZHANG DongDong FAN Zhen SUN ErPing ZHANG JunFeng LIU Hang XU HaiFeng JIN MingXing DING DaJun
With the concept of super-atom, first principles calculations propose a new type of super stable cage clusters AlnH3n that are much more energetic stable than the well established clusters, AlnHn＋2. In the new clusters, the aluminum core-frame acts as a super-atom with n vertexes and 2n A1-A1 edges, which allow to adsorb n hydrogen atoms at the top-site and 2n at the bridge-site. Using Al12H36 as the basic unit, stable chain structures, （Al12H36）m, have been constructed following the same connection mechanism as for （A1H3）n linear polymeric structures. Apart from high hydrogen percentage per molecule, calculations have shown that these new clusters possess large heat of formation values and their combustion heat is about 4.8 times of the methane, making them a promising high energy density material.
Ke-yan LianYuan-fei JiangDe-hou FeiWei FengMing-xing JinDa-jun DingYi Luo
This paper reports that a one-colour fs pump probe measurement has been carried out for studying photoionization/photodissociation of cyclohexanone （C6H10O） in intense laser field. Two of the fragments from eyclohexanone, C2H＋ and C3H3＋, are studied under 800 nm laser pump-probe and the results obtained show similar time evolutions. It proposes a feasible model for analysing the experimental observations of the one-colour fs pump-probe measurement. The results demonstrate that as an intermediate product, the excited molecular parent ions play a very important role in photionization/photodissociation processes in intense laser field.
