Moroshkin, Peter Hofer, Adrian Weis, Antoine 2008-08-23 The studies of defects formed by impurity particles (atoms, molecules, exciplexes, clusters, free electrons, and positive ions) embedded in liquid and solid ⁴He are reviewed. The properties of free electrons and neutral particles in condensed helium are described by the electron (atomic) bubble model, whereas for the positive ions a snowball structure is considered. We compare the properties of the defects in condensed helium with those of metal atoms isolated in heavier rare gas matrices. application/pdf https://folia.unifr.ch/global/documents/300961 https://folia.unifr.ch/documents/300961/files/moroshkin_amd.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.physrep.2008.06.004 info:eu-repo/semantics/openAccess License undefined Physics Reports. - 2008, vol. 469, no. 1, p. 1-57 matrix isolation spectroscopy solid helium superfluid helium atomic bubbles electron bubbles exciplexes optically detected magnetic resonance info:eu-repo/classification/udc/53 Atomic and molecular defects in solid ⁴He http://purl.org/coar/resource_type/c_6501