Strong Field Double Ionization of Formaldehyde

Strong field Ionization (SFI) plays a key role in many time resolved experiments, such as high harmonic generation and Coulomb explosion imaging. In our work, momentum resolved covariance measurements were performed on the fragments produced from the double ionization of formaldehyde (H₂CO) using SFI.¹ The momentum resolved covariance measurements allow for complete characterization of the dissociation products, and recovery of the molecular recoil frame ionization yields. But, understanding the underlying cause for the formation of fragments and getting state-resolved ionization yields through experiments is limited. Computational studies can help overcome these limitations. We have performed excited states molecular dynamics on several singlet and triplet states using trajectory surface hopping to calculate the kinetic energies (KE) of fragments formed from H₂CO²⁺. Our KE distributions were then fitted with experimental KE releases to get state-resolved double ionization yields. Electronic structure calculations were also performed in order to understand the underlying mechanics through which the dissociations occur. One of the interesting findings of this work is the presence of metastable H₂CO²⁺ found on the first excited singlet state (S₁).² This work is an example of how computational and experimental results can be combined to verify each other and fill up knowledge gaps.