New results for the formation of a muoniated radical in the Mu + Br2 system: a van der Waals complex or evidence for vibrational bonding in Br–Mu–Br?

• DOI: 10.1039/c2cp41366c
• Publication Date: 2012-06-22T17:21:21Z
• Authors: Donald G. Fleming; Stephen P. Cottrell; Iain McKenzie; Roderick M. Macrae
• Keywords: Bar (unit); Hyperfine coupling

New evidence is presented for the observation of a muoniated radical in Mu + Br(2) system, from μSR longitudinal field (LF) repolarisation studies gas phase, at concentrations 0.1 bar Br(2)/N(2) mixture 300 K and 10 total pressure. The LF curve, up to 4.5 kG, reveals two paramagnetic components, one atom, formed promptly during slowing-down process positive muon, with known hyperfine coupling constant (hfcc) 4463 MHz, by fast addition. From model fits data, component found have an unusually high muon hfcc, assessed be ∼3300 MHz overall error due systematics expected exceed 10%. This hfcc taken as either Br-Mu-Br radical, hence vibrational bonding this H[combining low line]-L[combining line]-H[combining line] or MuBr(2) van der Waals complex entrance channel. Preliminary ab initio electronic structure calculations suggest latter more likely but fully rigorous effect dynamics on system yet carried out.