High-resolution Fourier transform momentum spectroscopy of broad rotational wave packets in cationic states of diatomic molecules

We use velocity map imaging and Fourier transform spectroscopy to investigate rotational wave packets in bound cationic states of diatomic molecules. The wave packets are launched by strong-field ionization of the molecules by 800 nm, ≈100 fs pulses through pre- and post-ionization excitation. The molecules are dissociated by either the fundamental at 800 nm or the third harmonic. High resolution FFT spectroscopy allows us to identify the electronic, vibrational and rotational sates involved, and provides access to many examples where the coupling to rotational angular momentum to spin and electronic angular momentum is critical in determining the rotational dynamics. We will discuss these dynamics in D₂⁺, O₂⁺ and N₂⁺.