Muon spin rotation studies of organic liquids

Abstract

Several organic liquids have been studied using the muon spin rotation @.s.r.) technique. Radicals are seen in some of these compounds, formed by the addition of muonium (the muonic analogue of hydrogen) to an unsaturated molecule. Hyperfine interaction constants are calculated for the radicals and compared with those obtained for protonic radicals by other techniques. The magnitude of the diamagnetic fraction in the liquids is discussed.

Density Functional Studies of Hydrogen Atom Addition to the CS Bond

“…For the purpose of comparison, calculations were also carried out on the adducts of the O analogue of I , i.e., propan-2-one. Experimentally, this is known to yield addition at O . In this case, addition at O is energetically preferred by 45 kJ mol -1 , and the relevant proton hyperfine couplings are 815 and −18 MHz for addition at C and O, respectively.…”

“…Experimentally, this is known to yield addition at O. 37 In this case, addition at O is energetically preferred by 45 kJ mol -1 , and the relevant proton hyperfine couplings are 815 and -18 MHz for addition at C and O, respectively. (The very large size of A′ µ in the C adduct would probably preclude observation of this radical in conventional TFµSR experiments even if it were formed.…”

Muon Spin Rotation of Carbonyl Compounds, an Exploration of the Mechanism of Hyperfine Interaction

“…Muon spin rotation studies of a series of carbonyl compounds with only aliphatic groups attached to the CO group have been reported in the literature, − , Therefore only the vibrational spectra of these materials were needed for this investigation. The electronic effects of the aliphatic groups attached to a CO group will have to be conveyed via the σ-bonds and therefore to a good first approximation it will affect only the σ-bond strength of the CO group.…”

“…[2][3][4][5][6] There are a number of studies reporting muonium adducts with carbonyl groups. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Addition to -CdO groups contrast with the adducts formed with CdC groups due mainly to the presence of lone pairs of electrons on the oxygen atom. Muonium addition to CdC results in the complete opening of the double bond, with the unpaired electron residing mainly in a carbon 2p z orbital β to the muon site.…”

Absolute rate constants for radical rearrangements in liquids obtained by muon spin rotation

“…(10) ' _ , ( ± ) -e"vre'í(wn±ü,)7)---_ cosh ' -cos imü ± ) (11) where = N't is the length of the histogram and ' = X + X0. For \' « 1 and not near the low or the high end of the frequency spectrum23 F_ shows a peak for mil = and F+ can be neglected in that region.…”