How attosecond technology interrogates building blocks of molecular nanomaterials

Attosecond technologies based on high harmonic generation (HHG) allow us to probe the fundamental properties of light–matter interactions with an unprecedented level of temporal and spatial resolution. HHG-based light sources deliver attosecond pulses of extreme ultraviolet photons that can easily ionize isolated molecules in the gas phase. This ultrafast ionization results in various physical phenomena involving pure electronic or coupled electronic and nuclear mechanisms. These mechanisms lead to charge and energy dynamics at the angstrom length scale that impact the fate of the system on longer timescales. Significant progress has been made in studying small polyatomic molecules with attosecond pulses. These advances raise the question of whether the physical processes observed in small isolated molecules can also be studied as the size of the systems approaches the nanometric domain and eventually reaches the domain of molecular nanomaterials. In this article, we discuss examples of phenomena exhibiting scale invariances that can be used to predict the outcomes of interactions between light pulses and increasingly complex systems. Specifically, we discuss electron scattering on the attosecond timescale and electron–phonon dynamics in photoionized species, highlighting universal mechanisms that manifest in these building blocks of molecular nanomaterials. This work also raises new questions for future experiments in complex molecular materials.