Conversion of dissolved “water” into molecular hydrogen and peroxy linkages

Freund, Friedemann

doi:10.1016/0022-3093(85)90288-1

Cited by 26 publications

(14 citation statements)

References 32 publications

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“…We observed the silanol groups are very stable: once formed, the species exist until the end of simulation. We did not notice reaction between two adjacent silanols that create the peroxy link as proposed by previous work 43. The adjacent silanol in surface system A also presents the similar behavior.…”

Section: Resultssupporting

confidence: 82%

The first‐principles molecular dynamics study of quartz–water interface

Ledyastuti

Liang

Matsuoka

2012

Int J of Quantum Chemistry

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By first‐principles molecular dynamics, we have investigated the interaction of quartz (0001) surface with liquid water for two different fresh silica cleavages. The first type of cleavage is terminated by Si(O)2 and Si for two surfaces, respectively, whereas the second type cleavage has the same termination on both surfaces that consists of SiO. The water molecules were found to be decomposed and spontaneously form silanol group on both silica surfaces. After 4.0 ps, the chemical reactions were almost saturated. It was found that the silanol groups dominated on both surfaces. For the first type of cleavage, the final structure contains geminal, triple, and single silanols together with peroxy SiOOSi and SiOOH defects. For the second type of cleavage, the final structure contains geminal silanol, single silanol, and siloxane bridge. A small amount of unsaturated sites were also found on both surfaces. Further, we have shown that the newly formed rings at quartz surface range from four‐ to seven‐member ring for both surfaces. All the findings are in good consistent with the recent experimental observations and theoretical respects. © 2012 Wiley Periodicals, Inc.

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Section: Resultssupporting

confidence: 82%

The first‐principles molecular dynamics study of quartz–water interface

Ledyastuti

Liang

Matsuoka

2012

Int J of Quantum Chemistry

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“…The reaction involves hydroxyl pairs, which are ubiquitous in all minerals that have crystallized in the presence of H 2 O, even those that are nominally anhydrous. Hydroxyl pairs in the matrix of these nominally an-hydrous minerals can split off H 2 while simultaneously converting their O 2− to the 1-(peroxy) state (Freund, 1985).…”

Section: Discussionmentioning

confidence: 99%

Stimulated infrared emission from rocks: assessing a stress indicator

Freund¹,

Takeuchi²,

Lau³

et al. 2007

eEarth

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To study the effect of stress-activated positive hole (p-hole) charge carriers on the infrared (IR) emission from rocks, we subjected a portion (∼10 vol.%) of a large (30×60×7.5 cm 3) block of anorthosite, a nearly monomineralic (Ca-rich feldspar) igneous rock, to uniaxial deviatory stress up to failure. We measured the IR emission from a flat surface ≈40 cm from the stressed rock volume over the 800-1300 cm −1 (7.7-12.5 µm) range. Instantly, upon loading, the emission spectrum and intensity change. At first narrow bands appear at 930 cm −1 (10.75 µm), 880 cm −1 (11.36 µm), 820 cm −1 (12.4 µm) plus additional narrow bands in the 1000-1300 cm −1 (7.7-10.0 µm) range. The 10.75-12.4 µm bands are thought to arise from vibrationally excited O-O stretching modes, which form when p-hole charge carriers, which spread from the stressed rock volume into the unstressed rock, recombine at the surface. They radiatively decay, giving rise to "hot" bands due to transitions between excited states. Before failure the broad emission bands at 1170 cm −1 and 1030 cm −1 (8.7 and 9.7 µm) also increase slightly in intensity, suggesting a small increase in temperature due to thermalization of the energy deposited into the surface through p-hole recombination. Stimulated IR emission due to hole-hole recombination and its followon effects may help understand the enhanced IR emission seen in night-time satellite images of the land surface before major earthquakes known as "thermal anomalies".

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“…The same type of peroxy defects exist in the structures of rock-forming minerals, O 3 X-OO-YO 3 with X, Y = Si 4+ , Al 3+ , etc. They are introduced through the incorporation of H 2 O into nominally anhydrous minerals that crystallize in H 2 O-laden magmas or recrystallize in high-temperature H 2 O-laden environments (Freund, 1985). The incorporation of H 2 O can be described as splitting of an O 3 SiOSiO 3 bond, leading to hydroxyls, O 3 Si-OH, most commonly in pairs.…”

Section: Solid State Background: Positive Hole Charge Carriersmentioning

confidence: 99%