Argon compounds

Argon compounds, the chemical compounds that contain the element argon, are rarely encountered due to the inertness of the argon atom. However, compounds of argon have been detected in inert gas matrix isolation, cold gases, and plasmas, and molecular ions containing argon have been made and also detected in space. One solid interstitial compound of argon, Ar₁C₆₀ is stable at room temperature. Ar₁C₆₀ was discovered by the CSIRO.

Argon ionises at 15.76 eV, which is higher than hydrogen, but lower than helium, neon or fluorine.^[1] Molecules containing argon can be van der Waals molecules held together very weakly by London dispersion forces. Ionic molecules can be bound by charge induced dipole interactions. With gold atoms there can be some covalent interaction.^[2] Several boron-argon bonds with significant covalent interactions have been also reported.^[3][4] Experimental methods used to study argon compounds have included inert gas matrices, infrared spectroscopy to study stretching and bending movements, microwave spectroscopy and far infrared to study rotation, and also visible and ultraviolet spectroscopy to study different electronic configurations including excimers. Mass spectroscopy is used to study ions.^[5] Computation methods have been used to theoretically compute molecule parameters, and predict new stable molecules. Computational ab initio methods used have included CCSD(T), MP2 (Møller–Plesset perturbation theory of the second order), CIS and CISD. For heavy atoms, effective core potentials are used to model the inner electrons, so that their contributions do not have to be individually computed. More powerful computers since the 1990s have made this kind of in silico study much more popular, being much less risky and simpler than an actual experiment.^[5] This article is mostly based on experimental or observational results.

The argon fluoride laser is important in photolithography of silicon chips. These lasers make a strong ultraviolet emission at 192 nm.^[6]