title: Self-Assembly of Iodine in Superfluid Helium Droplets: Halogen Bonds and Nanocrystals.
abstract: We present evidence of halogen bond in iodine clusters formed in superfluid helium droplets based on results from electron diffraction. Iodine crystals are known to form layered structures with intralayer halogen bonds, with interatomic distances shorter than the sum of the van der Waals radii of the two neighboring atoms. The diffraction profile of dimer dominated clusters embedded in helium droplets reveals an interatomic distance of 3.65 Å, much closer to the value of 3.5 Å in iodine crystals than to the van der Waals distance of 4.3 Å. The profile from larger iodine clusters deviates from a single layer structure; instead, a bi-layer structure qualitatively fits the experimental data. This work highlights the possibility of small halogen bonded iodine clusters, albeit in a perhaps limited environment of superfluid helium droplets. The role of superfluid helium in guiding the trapped molecules into local potential minima awaits further investigation.
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Yunteng
authors.identifier: 0000-0001-9947-8933
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Lei
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR, 97331, USA.
authors.forename: Wei
authors.identifier: 0000-0003-3882-5019
authors.initials: W
authors.lastname: Kong
mesh_terms: D003460:Crystallization; D004583:Electrons; D006219:Halogens / Q000737:chemistry*; D006371:Helium / Q000737:chemistry*; D007455:Iodine / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods
chemical_list: D006219:Halogens; D006371:Helium; D007455:Iodine
keywords: chemical physics; crystal growth; electron diffraction; gas-phase reactions; nanotechnology