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Correction for ‘Sub-Doppler infrared spectroscopy of resonance-stabilized hydrocarbon intermediates: ν 3 / ν 4 CH stretch modes and CH 2 internal rotor dynamics of benzyl radical’ by A. Kortyna et al. , Phys. Chem. Chem. Phys. , 2017, 19 , 29812–29821. 

Bismuth has been the key element in the discovery and development of topological insulator materials. Previous theoretical studies indicated that Bi is topologically trivial and it can transform into the topological phase by alloying with Sb. However, recent high-resolution angle-resolved photoemission spectroscopy (ARPES) measurements strongly suggested a topological band structure in pure Bi, conflicting with the theoretical results. To address this issue, we studied the band structure of Bi and Sb films by ARPES and first-principles calculations. The quantum confinement effectively enlarges the energy gap in the band structure of Bi films and enables a direct visualization of the Z 2 topological invariant of Bi. We find that Bi quantum films in topologically trivial and nontrivial phases respond differently to surface perturbations. This way, we establish experimental criteria for detecting the band topology of Bi by spectroscopic methods. 

ABSTRACT We present Atacama Compact Array and Atacama Pathfinder Experiment observations of the [N ii] 205 μm fine-structure line in 40 sub-millimetre galaxies lying at redshifts z = 3–6, drawn from the 2500 deg2 South Pole Telescope survey. This represents the largest uniformly selected sample of high-redshift [N ii] 205 μm measurements to date. 29 sources also have [C ii] 158 μm line observations allowing a characterization of the distribution of the [C ii] to [N ii] luminosity ratio for the first time at high redshift. The sample exhibits a median L$_{{\rm{[C\,{\small II}]}}}$/L$_{{\rm{[N\,{\small II}]}}}$ ≈ 11.0 and interquartile range of 5.0 –24.7. These ratios are similar to those observed in local (Ultra)luminous infrared galaxies (LIRGs), possibly indicating similarities in their interstellar medium. At the extremes, we find individual sub-millimetre galaxies with L$_{{\rm{[C\,{\small II}]}}}$/L$_{{\rm{[N\,{\small II}]}}}$ low enough to suggest a smaller contribution from neutral gas than ionized gas to the [C ii] flux and high enough to suggest strongly photon or X-ray region dominated flux. These results highlight a large range in this line luminosity ratio for sub-millimetre galaxies, which may be caused by variations in gas density, the relative abundances of carbon and nitrogen, ionization parameter, metallicity, and a variation in the fractional abundance of ionized and neutral interstellar medium. 

Highly reactive benzyl radicals are generated by electron dissociative attachment to benzyl chloride doped into a neon–hydrogen–helium discharge and immediately cooled to T rot = 15 K in a high density, supersonic slit expansion environment. The sub-Doppler spectra are fit to an asymmetric-top rotational Hamiltonian, thereby yielding spectroscopic constants for the ground ( v = 0) and first excited ( v = 1, ν 3 , ν 4 ) vibrational levels of the ground electronic state. The rotational constants obtained for the ground state are in good agreement with previous laser induced fluorescence measurements (LIF), with vibrational band origins ( ν 3 = 3073.2350 ± 0.0006 cm −1 , ν 4 = 3067.0576 ± 0.0006 cm −1 ) in agreement with anharmonically corrected density functional theory calculations. To assist in detection of benzyl radical in the interstellar medium, we have also significantly improved the precision of the ground state rotational constants through combined analysis of the ground state IR and LIF combination differences. Of dynamical interest, there is no evidence in the sub-Doppler spectra for tunneling splittings due to internal rotation of the CH 2 methylene subunit, which implies a significant rotational barrier consistent with partial double bond character in the CC bond. This is further confirmed with high level ab initio calculations at the CCSD(T)-f12b/ccpVdZ-f12 level, which predict a zero-point energy corrected barrier to internal rotation of Δ E tun ≈ 11.45 kcal mol −1 or 4005 cm −1 . In summary, the high-resolution infrared spectra are in excellent agreement with simple physical organic chemistry pictures of a strongly resonance-stabilized benzyl radical with a nearly rigid planar structure due to electron delocalization around the aromatic ring.