The optical absorption and fluorescence spectra of alkali atoms isolated in liquid and solid He matrices depend on specific macroscopic matrix properties, such as their molar volume and (anisotropic) elasticity constants, ...

A little more than a decade ago our team extended the field of defect spectroscopy in cryocrystals to solid ⁴He matrices, in both their body-centered cubic (bcc) and hexagonally close-packed (hcp) configurations. In this ...