Ultrafast Molecular Imaging Using 4-Fold Covariance: Coincidence Insight with Covariance Speed

Momentum resolved coincidence measurements have traditionally served as the gold standard for measuring dissociative ionization of molecules. Covariance measurements can provide similar physical insights and have enabled much higher data taking rates (∼ 100×) [1], allowing for studies as a function of laser intensity, pulse duration, pump-probe delay etc. While powerful, covariance was only demonstrated for up to three particles, limiting its use in Coulomb explosion imaging (CEI) of larger molecules [2]. Here we develop some mathematical tools to compute higher order covariances, and demonstrate four fold covariance for CEI of deuterated formaldehyde (CD2O).

[1] Allum, F., Cheng, C., Howard, A.J., Bucksbaum, P.H., Brouard, M., Weinacht, T. and Forbes, R., 2021. Multi-Particle Three-Dimensional Covariance Imaging:“Coincidence” Insights into the Many-Body Fragmentation of Strong-Field Ionized D2O. The Journal of Physical Chemistry Letters, 12(34), pp.8302-8308.

[2] Zhaunerchyk, V., Frasinski, L.J., Eland, J.H. and Feifel, R., 2014. Theory and simulations of covariance mapping in multiple dimensions for data analysis in high-event-rate experiments. Physical Review A, 89(5), p.053418.