Calcite dissolution rate spectra measured by in situ digital holographic microscopy

Brand, Alexander S.; Pan, Feng; Bullard, Jeffrey W.

doi:10.1016/j.gca.2017.07.001

Cited by 55 publications

(90 citation statements)

References 47 publications

(90 reference statements)

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“…Nevertheless, the spectral representation of rate maps ("rate spectra", [1]) does preserve the contribution of all surface features to the overall rate [25], and has seen limited but increasing adoption in the literature [12,17]. It can be clearly seen in Figure 5 that the spectra generated from calcite dissolution rate maps (see also Figure 4) are an asymmetric distribution, one that is consistent with a heterogeneous, Boltzmann distribution of reactive surface sites.…”

Section: Interpretation Of Reaction Mechanism Via Rate Spectral Analysismentioning

confidence: 99%

“…[5]). Both microscopes afford direct observation of mineral surfaces, and in situ AFM [6][7][8][9][10][11][12] and VSI [1,[13][14][15][16][17] have greatly expanded the understanding of reaction kinetics for a diverse range of carbonates, silicates, and other important phases. Calcite has been a favorite AFM and VSI target, due to its clear importance in environmental systems, its simple composition, and perfect cleavage.…”

Section: Introductionmentioning

confidence: 99%

“…[4], for discussion), and the complexity of direct, truly in situ measurements, which must be compensated for the fluid's contribution to the optic signal (see also in situ digital holographic microscopy in ref. [17]). These limits are often the motivation for using AFM and VSI instruments in concert as complementary tools.…”

Section: Introductionmentioning

confidence: 99%

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Temporal Evolution of Calcite Surface Dissolution Kinetics

et al. 2018

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Abstract:This brief paper presents a rare dataset: a set of quantitative, topographic measurements of a dissolving calcite crystal over a relatively large and fixed field of view (~400 µm 2 ) and long total reaction time (> 6 h). Using a vertical scanning interferometer and patented fluid flow cell, surface height maps of a dissolving calcite crystal were produced by periodically and repetitively removing reactant fluid, rapidly acquiring a height dataset, and returning the sample to a wetted, reacting state. These reaction-measurement cycles were accomplished without changing the crystal surface position relative to the instrument's optic axis, with an approximate frequency of one data acquisition per six minutes' reaction (~10/h). In the standard fashion, computed differences in surface height over time yield a detailed velocity map of the retreating surface as a function of time. This dataset thus constitutes a near-continuous record of reaction, and can be used to both understand the relationship between changes in the overall dissolution rate of the surface and the morphology of the surface itself, particularly the relationship of (a) large, persistent features (e.g., etch pits related to screw dislocations; (b) small, short-lived features (e.g., so-called pancake pits probably related to point defects); (c) complex features that reflect organization on a large scale over a long period of time (i.e., coalescent "super" steps), to surface normal retreat and step wave formation. Although roughly similar in frequency of observation to an in situ atomic force microscopy (AFM) fluid cell, this vertical scanning interferometry (VSI) method reveals details of the interaction of surface features over a significantly larger scale, yielding insight into the role of various components in terms of their contribution to the cumulative dissolution rate as a function of space and time.

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Section: Interpretation Of Reaction Mechanism Via Rate Spectral Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Temporal Evolution of Calcite Surface Dissolution Kinetics

et al. 2018

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“…It is a quantitative phase microscopy technique capable of being configured for reflection or transmission microscopy, and it has been used for a variety of applications [1], including static and dynamic surface metrology [2][3][4][5][6][7], particle tracking [8,9], tracking and monitoring of live biological cells [3,[10][11][12], and monitoring surface dissolution [13,14] or growth [15] kinetics. DHM and related quantitative phase imaging technologies have been extensively developed for the study of biological specimens [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Phase Uncertainty in Digital Holographic Microscopy Measurements in the Presence of Solution Flow Conditions

Brand¹

2017

J. RES. NATL. INST. STAN.

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Digital holographic microscopy (DHM) is a surface topography measurement technique with reported sub-nanometer vertical resolution. Although it has been made commercially available recently, few studies have evaluated the uncertainty or noise in the phase measurement by the DHM. As current research is using the DHM to monitor surface topography changes of dissolving materials under flowing water conditions, it is necessary to evaluate the effect of water and flow rate on the uncertainty in the measurement. Uncertainty in this study was concerned with the temporal standard deviation per pixel of the reconstructed phase. Considering the effects of solution flow rate, magnification, objective lens type (air or immersion), and experimental configuration, measurements under static conditions in air and in water with an immersion lens yielded the smallest amount of uncertainty (mean of ≤ 0.5 nm up to 40× magnification). Increasing the water flow rate resulted in an increase in mean uncertainty to ≤ 0.6 nm up to 40× with an immersion lens. Observations of a sample through a glass window at 20× magnification in flowing water also yielded increasing uncertainty, with mean values of ≤ 0.5 nm, ≤ 0.8 nm, and ≤ 1.1 nm for flow rates of 0 mL min ) did not significantly impact the uncertainty in the phase. Collecting holograms in single-wavelength versus dual-wavelength modes did impact the uncertainty, with the mean uncertainty at 10× magnification for the same wavelength being ≤ 0.5 nm from the single-wavelength mode compared to ≤ 1.5 nm from the dualwavelength mode. When the quantified uncertainty was applied to simulated dissolution data, lower limits of measured dissolution rates were found below which the measured data may not be distinguishable from the uncertainty in the measurement. The limiting surface-normal dissolution velocity is −10 −11.7 m s ) flowing water conditions in experiments with a glass window, respectively. The data presented by this study will allow for better experimental design and methodology for future dissolution or precipitation studies using DHM and will provide confidence in the data produced in postprocessing.

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“…1), calcite grains are mechanically locked together prior to interaction with the fluid; as the edges of the grains dissolve, the grains become unlocked, allowing intergranular repulsion to eject them from the surface. To further explore the precise mechanism by which grains are removed from the surface, we would ideally carry out a series of experiments using completely noncontact imaging, such as the relatively new method of in situ digital holographic microscopy (Brand et al, 2017). Irrespective of whether the grains are removed by intergranular repulsion, by interaction with the AFM tip, or by drying, our experiments demonstrate that tiny purturbations in the system can cause grains to be detached from the surfaces of reacting limestone.…”

mentioning

confidence: 99%

Reply to comment on “Repulsion between calcite crystals and grain detachment during water-rock interaction” by Le Merrer and Colombani, 2017

Levenson¹,

Emmanuel²

2017

Geochem. Persp. Let.

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The comment by Le Merrer and Colombani (2017) focuses on the mechanisms that could account for our experiments, in which we observed the detachment of micrometre scale calcite grains from the surface of micritic limestone during contact with a reactive fluid (Levenson and Emmanuel, 2017). They discuss some of the forces acting on the grains and imply that our observations are likely to be artefacts of the experimental method. Furthermore, they suggest that because our measured calcite dissolution rates do not match exactly the dependence on ionic strength predicted by Colombani (2016), an "unidentified phenomenon" could be at play in our experiments. While Le Merrer and Colombani (2017) raise some valid points, we think that an alternative interpretation is possible. We are pleased to be able to discuss these aspects of our paper in greater detail.In experiments carried out under a range of flow conditions, we have observed the detachment of micrometre size grains from the surface of micritic limestone (Emmanuel and Levenson, 2014; Emmanuel, 2016, 2017). Le Merrer and Colombani (2017) show that under our experimental conditions neither thermal agitation nor fluid shearing are strong enough to overcome gravity and remove grains from the surface. Moreover, they assert that although the repulsive forces related to the electric double layer and hydration are much stronger than the gravitational force, repulsion cannot remove grains from the surface because it only operates over the relatively short range of several nanometres. However, by considering the energy gains and losses involved in removing a grain from the surface, it can be shown that this is not necessarily the case. From the relationship describing the effective weight of a grain, F = (r calcite -r water )gV grain , where r calcite represents the density of calcite (2710 kg m -3 ), r water , the density of water (1000 kg m -3 ), g, gravitational acceleration (9.81 m s -2 ), and V grain , the grain volume, it follows that a 1 mm calcite grain surrounded by water would gain ~2 × 10 -20 J in gravitational potential energy for every micrometre it is removed from the surface in the vertical direction. According to the experiments carried out by Røyne et al. (2015), calcite surfaces in close proximity in pure water experience only repulsive forces so a calcite grain in contact with another calcite surface would possess a certain potential energy that could be translated into gravitational or kinetic energy. An estimate of this energy can be made by integrating the area under the force-distance curves, reported by Røyne et al. (2015), and then normalising by the surface area of the crystals used in their experiments. The crystal surface areas were reported to be in the range of 300 to 3500 mm 2 , and accordingly, we estimate the potential energy to be ~0.1-1.7 × 10 -20 J mm -2 . Using these values, a 1 mm calcite grain with an area of 5 mm 2 , in contact with another calcite surface, has ~0.5-8 × 10 -20 J of potential energy. Significantly, the higher end of th...

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Calcite dissolution rate spectra measured by in situ digital holographic microscopy

Cited by 55 publications

References 47 publications

Temporal Evolution of Calcite Surface Dissolution Kinetics

Temporal Evolution of Calcite Surface Dissolution Kinetics

Phase Uncertainty in Digital Holographic Microscopy Measurements in the Presence of Solution Flow Conditions

Reply to comment on “Repulsion between calcite crystals and grain detachment during water-rock interaction” by Le Merrer and Colombani, 2017

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