Structural and dynamical phase jumps in molecular high harmonic spectroscopy

High harmonic spectroscopy is a powerful tool that provides insights into molecular structure and multielectron dynamics with attosecond-ångström resolution. The spectral features of high harmonic emissions encode vital information about the underlying molecular structure and dynamics, influenced primarily by two interference effects: structural two-center interference and multichannel dynamic interference. These interferences manifest as intensity minima in the harmonic spectra. Additionally, the spectral phase, critical for wavefunction reconstruction and understanding molecular dynamics, displays distinct behaviors linked to these interferences. In this work, we conduct a comprehensive analysis of the contrasting phase jumps associated with these interference mechanisms within the framework of the strong-field approximation (SFA). Our findings reveal the physical origins of the observed spectral phase variations and underscore the potential of spectral phase information in probing molecular dynamics at ultrafast timescales.