Spectroscopic Investigations of Diatomic Molecules

Spectroscopic studies of diatomic molecules probe the quantised rotational, vibrational and electronic energy levels that govern molecular behaviour across environments as diverse as interstellar clouds, planetary atmospheres and laboratory plasmas. By recording absorption and emission spectra from the microwave through the vacuum ultraviolet, researchers extract fundamental molecular constants, map potential energy curves and characterise perturbations between closely spaced electronic states. Advances in high-resolution Fourier-transform techniques, synchrotron radiation sources and ion-storage traps have enabled measurement of transition frequencies and lifetimes with sub-wavenumber accuracy. Complementary ab initio computations now provide predictive models of dipole moments and potential energy surfaces, guiding assignments of complex spectra and deperturbation analyses. Together, experimental and theoretical progress refines our understanding of molecular structure, informs astrochemical models, supports atmospheric monitoring and underpins emerging applications in laser cooling and quantum control of molecular ions.

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Spectroscopic Investigations of Diatomic Molecules publication trend

The graph below shows the total number of articles in spectroscopic investigations of diatomic molecules across all publications each year (not limited to Nature Index journals).

Technical terms

Rovibrational transitions: Simultaneous changes in rotational and vibrational quantum levels that give rise to characteristic spectral lines in the infrared and microwave regions.

Autodetachment: Spontaneous emission of an electron from a molecular anion in an excited electronic or rotational state.

Franck–Condon principle: The approximation that electronic transitions occur much faster than nuclear motion, determining the intensity distribution of vibronic lines.

Deperturbation analysis: A theoretical procedure to disentangle interactions between overlapping electronic states and extract unperturbed molecular constants.

Potential energy surface: A multidimensional representation of the energy of a molecule as a function of nuclear coordinates, central to modelling its spectroscopic and dynamical properties.

References

1. Autodetachment of Diatomic Carbon Anions from Long-Lived High-Rotation Quartet States. Physical Review Letters (2024).
2. Vibrationally Resolved Inner‐Shell Photoexcitation of the Molecular Anion C2−. ChemPhysChem (2023).
3. Photodetachment Spectroscopy of Highly Excited \(\text{C}_{2}^{ - }\) and Their Temporal Evolution in the Ion Storage Ring RICE. Journal of the Physical Society of Japan (2022).