Surface Hydroxyl Identity and Reactivity in Akaganéite

Abstract

Hydroxyl groups on surfaces of well-defined akagan eite (β-FeOOH) particles were identified by Fourier transform infrared spectroscopy. These efforts, assisted by molecular dynamics simulations, enabled the extraction of spectral signatures for these groups of the dominant ( 100), (001), and (010) crystallographic planes. Band assignments were supported by spectral variations induced by proton and chloride adsorption as well as temperature-programmed desorption. Molecular dynamics simulations were used to determine patterns and free energies of formation of hydrogen bonds. Surface FeÀO distances as well as hydrogen-bond numbers were also used to predict proton affinities. All spectral component concentrations display highly comparable responses to proton loadings with those of other FeOOH minerals previously studied with our coupled experimen-talÀtheoretical approach. These similarities underpin common thermodynamic stabilities for hydroxyls of a given Fe nuclearity on different planes of different minerals.

Fabrication of rod-shaped β-FeOOH: the roles of polyethylene glycol and chlorine anion

“…proached about 47%. This ratio is much higher than that in previous reports where the exposure of the {010} facets was no more than 5% [24]. The {010} facets are rich in doubly and triply coordinated hydroxyl groups that particularly favored the formation of hydrogen bonds [24], which might be of utmost importance in chemical reactions or dispersing metal nanoparticles.…”

“…This ratio is much higher than that in previous reports where the exposure of the {010} facets was no more than 5% [24]. The {010} facets are rich in doubly and triply coordinated hydroxyl groups that particularly favored the formation of hydrogen bonds [24], which might be of utmost importance in chemical reactions or dispersing metal nanoparticles. Here, the preferential exposure of the {010} facets might be related with the stronger adsorption of Cl  on the reactive planes [10], which directed the growth of β-FeOOH nanorods along the [001] direction.…”

Green's function method for the spin and pseudospin symmetries in the single-particle resonant states

“…× 2.56 2h 11/2 Im g (22) 3d 3/2 Im g (22) × 4.23 3d 5/2 Im g (22) 2h 9/2 Im g (11) × 2.56 2h 11/2 Im g (11) 3d 3/2 Im g (11) × 4.23 3d 5/2 Im g (11) (a) Im g (11) , Im g (22) [fm (11) × 246.61 1j 15/2 Im g (11) 1j 13/2 Im g (22) × 246.61 1j 15/2 Im g (22) (c) FIG. 7: Distribution function ρ g (r) = ImG (11) κ (r, r; ε + iε) and ρ f (r) = ImG (22) κ (r, r; ε + iε) in the coordinate space for the singleneutron resonance spin doublets (a) 3d, (b) 2h, and (c) 1 j in 208 Pb at the resonant energy ε = ε j > ( j < ) extracted from n(ε). For comparison, the functions for the spin doublets with smaller angular momenta j < are multiplied by a factor of 4.23, 2.56, and 246.61, respectively.…”

“…(9) at ε = ε j > ( j < ) have the same hight. ρ f (r) = ImG (22) κ (r, r; ε + iε) have a certain relationship with the wave functions, which are the integrands for the density of states n κ (ε) and correspond to the upper Dirac spinor G(r) and lower Dirac spinor F(r), respectively. Therefore, we show in Figs.…”

“…With a more general condition, Meng et al pointed out that dΣ(r)/dr = 0 can be approximately satisfied in exotic nuclei with highly diffuse potentials [13,14] and the onset of the pseudospin symmetry to a competition between the pseudo-centrifugal barrier (PCB) and the pseudospin-orbit (PSO) potential. Afterwards, the SS and PSS in nuclear spectra have been studied extensively such as PSS in deformed nuclei [15][16][17][18][19][20], PSS and SS * Electronic address: ttsunphy@zzu.edu.cn in hypernuclei [21][22][23][24][25][26], SS in anti-nucleon spectra [27][28][29][30][31], perturbative interpretation of SS and PSS [31][32][33][34][35], and PSS in supersymmetric quantum mechanics [36][37][38][39].…”