Coulomb explosion dynamics of thioesters*

Laser-induced Coulomb explosion imaging (CEI), a powerful probing technique commonly used in ultrafast experiments, has been coupled to covariance map analysis to unravel the multi-body dissociation dynamics of complex molecular systems. In order to extract dissociation dynamics from such images, it is crucial to determine the correlation between fragments’ momenta produced at each dissociative ionization event. In the high count rate regime, to calculate the correlation between momenta of different ionic fragments, we need to use statistical methods such as covariance map analysis. Here, we used a coincidence detection technique which was initially developed by Lee et al.¹ to acquire 3D multi-mass momentum images necessary to determine the covariance between ion pairs’ momenta. The covariance images are acquired using the reconstructed multi-mass images of coincident events. Using the combination of aforementioned techniques, we have been able to study the dissociation dynamics of two thioester molecules which show interesting double-ionization decay pathways². In these studies, we induced Coulomb explosion in chlorocarbonylsulfenyl chloride and methoxycarbonylsulfenyl chloride molecules using high intensity laser beams. We have been able to reveal several fragmentation channels using two and three-fold covariance images and identify the origin of surprising correlations seen previously in the latter system. These experimental results are supported with ab initio calculations of the decomposition pathways of multiply charged parent ions.

1.           S. K. Lee, F. Cudry, Y. F. Lin, S. Lingenfelter, A. H. Winney, L. Fan and W. Li, Rev. Sci. Inst, 2014.

2.           M. F. Erben, M. Geronés, R. M. Romano and C. O. Della Védova, J. Phys. Chem. A, 2007.