Dynamical coupling of molecular rotation and Coulomb explosion

Abstract

Summary form only given. The first observation of 1/8<;sup>th<;/sup> rotational revival in impulsively aligned CO<;sub>2<;/sub> molecules probed by Coulomb explosion is reported. Such a dynamic gives insight in the coupling arising between rotation wavepacket and strong field dynamic. Field free molecular rotational alignment is nowadays a routine technique to achieve structural and dynamical measurements in the molecular frame [1]. It is a unique tool to study electron recollision in strong field physics as in High Harmonic Generation (HHG) spectroscopy and recollision-induced double ionisation and fragmentation. A rotational wavepacket is launch by an ultrashort pulse leading to periodic alignment of the molecules, so called “revivals”. Various experimental techniques are able to give insight in the rotational dynamic of the wavepacket as for example the direct visualization of the molecular bond orientation using velocity map imaging [2]. While the temporal evolution of such alignment is well represented by the expectation value <;cos<;sup>2<;/sup> θ> (0 is the angle between molecular bond and electric field polarisation), the experimental measurement of rotational periodic alignment can lead to significantly distorted revivals, especially with the presence of higher order terms as <;cos<;sup>n<;/sup> 0>with n=4,6. This has been shown especially with HHG, where the coupling of rotational wavepacket and angular yield of HHG is modulated differently, depending the molecule structure [3,4].