Electronic Structure and Spectroscopic Properties of Molecular Systems

Electronic structure defines the arrangement and energy levels of electrons in a molecule, governing its chemical reactivity, optical absorption and magnetic behaviour. Spectroscopic techniques—ranging from ultraviolet–visible and infrared absorption to X-ray photoelectron and near-edge X-ray absorption fine-structure (NEXAFS) methods—probe transitions between electronic and vibrational states, yielding molecular fingerprints and insights into bonding, charge distribution and spin states. Advances in computational methods, including density functional theory and multireference approaches, now enable accurate prediction of ground and excited states, conical intersections and non-radiative decay pathways. These combined theoretical and experimental tools underpin developments in energy conversion, molecular electronics, catalysis and spintronics by revealing the fundamental principles that govern molecular function and facilitating the rational design of new materials.

Research from Nature Portfolio

Recent studies have engineered two-dimensional networks of azafullerene radicals by encapsulating C59N• within cycloparaphenylene nanohoops on metal surfaces, achieving self-assembled lattices with preserved spin-½ character and demonstrable guest–host electronic coupling. The protective nanohoop environment inhibits radical dimerisation and substrate quenching, offering a route to high-density molecular spin arrays. In parallel, an extended cluster-expansion framework has been developed to predict the ground-state energetics of heterofullerenes by fitting a minimal set of interaction parameters to first-principles data, delivering millielectron-volt precision in stability rankings across numerous isomers and guiding targeted synthesis of doped carbon cages.

Electronic Structure and Spectroscopic Properties of Molecular Systems publication trend

The graph below shows the total number of articles in electronic structure and spectroscopic properties of molecular systems across all publications each year (not limited to Nature Index journals).

Technical terms

Electronic coupling: Interaction between electronic states of adjacent molecular units that facilitates charge or energy transfer.

Frontier molecular orbitals: Highest occupied and lowest unoccupied orbitals that dominate a molecule’s reactivity and optical transitions.

Biradical character: The degree to which two unpaired electrons in a molecule remain spatially separated with weak mutual interaction.

NEXAFS: Near-edge X-ray absorption fine-structure spectroscopy, a technique that probes unoccupied electronic states by measuring absorption near an element’s core-level edge.

Franck–Condon factors: Probabilities governing the intensity distribution of vibronic transitions based on overlap of vibrational wavefunctions.

Rydberg state: An excited state where an electron is promoted to a high-lying orbital with principal quantum number much greater than in the ground state.

Herzberg–Teller effect: Vibronic coupling mechanism by which electronic transitions gain intensity through vibrational motions that break symmetry.

Conical intersection: A point of degeneracy between electronic potential-energy surfaces that enables ultrafast non-radiative transitions.

References

1. Engineering 2D spin networks by on-surface encapsulation of azafullerene radicals in nanotemplates. Nature Communications (2025).
2. Rational Design of a Phosphorus‐Centered Disbiradical. Angewandte Chemie International Edition (2024).
3. Noncontact Layer Stabilization of Azafullerene Radicals: Route toward High-Spin-Density Surfaces. ACS Nano (2023).
4. An extended cluster expansion for ground states of heterofullerenes. Scientific Reports (2017).
5. The vacuum ultraviolet absorption spectrum of norbornadiene: Vibrational analysis of the singlet and triplet valence states of norbornadiene by configuration interaction and density functional calculations. The Journal of Chemical Physics (2021).
6. High-level studies of the singlet states of quadricyclane, including analysis of a new experimental vacuum ultraviolet absorption spectrum by configuration interaction and density functional calculations. The Journal of Chemical Physics (2023).