Mercury Layer Research Articles

Thermoelectricity at a gallium–mercury liquid metal interface

We present experimental evidence of a thermoelectric effect at the interface between two liquid metals. Using superimposed layers of mercury and gallium in a cylindrical vessel operating at room temperature, we provide a direct measurement of the electric current generated by the presence of a thermal gradient along a liquid–liquid interface. At the interface between two liquids, temperature gradients induced by thermal convection lead to a complex geometry of electric currents, ultimately generating current densities near boundaries that are significantly higher than those observed in conventional solid-state thermoelectricity. When a magnetic field is applied to the experiment, an azimuthal shear flow, exhibiting opposite circulation in each layer, is generated. Depending on the value of the magnetic field, two different flow regimes are identified, in good agreement with a model based on the spatial distribution of thermoelectric currents, which has no equivalent in solid systems. Finally, we discuss various applications of this effect, such as the efficiency of liquid metal batteries.

Wave Processes in Dusty Plasma near the Mercury’s Surface

Wave processes in dusty plasma near the surface of Mercury are discussed. The near-surface layers of Mercury’s exosphere have a number of common features with those of the exosphere of the Moon, e.g., there are dust particles above the illuminated side of both cosmic bodies that become positively charged due to the photoelectric effect. Mercury has its own magnetosphere that protects the surface from particles of the solar wind. However, the solar wind can reach the surface of the planet near the magnetic poles. Therefore, dust particles of the same size get different charges depending on their localization above the Mercury’s surface. A drift wave turbulence can appear in dusty plasma in the magnetic field near the Mercury’s surface in the presence of gradient of electron concentration. The solar wind that streams at speeds of about 400 km/s relative to plasma near the surface of the planet can induce longitudinal electrostatic oscillations with frequencies determined by the electron plasma frequency. We analyze wave processes taking into account the difference in parameters at aphelion and perihelion of the Mercury’s orbit, along with the fact whether the dust particles are located near the magnetic poles or far from them.

U, Th, and K partitioning between metal, silicate, and sulfide and implications for Mercury's structure, volatile content, and radioactive heat production

AbstractThe distribution of heat-producing elements (HPE) potassium (K), uranium (U), and thorium (Th) within planetary interiors has major implications for the thermal evolution of the terrestrial planets and for the inventory of volatile elements in the inner solar system. To investigate the abundances of HPE in Mercury’s interior, we conducted experiments at high pressure and temperature (up to 5 GPa and 1900 °C) and reduced conditions (IW-1.8 to IW-6.5) to determine U, Th, and K partitioning between metal, silicate, and sulfide (Dmet/sil and Dsulf/sil). Our experimental data combined with those from the literature show that partitioning into sulfide is more efficient than into metal and that partitioning is enhanced with decreasing FeO and increasing O contents of the silicate and sulfide melts, respectively. Also, at low oxygen fugacity (log fO2 < IW-5), U and Th are more efficiently partitioned into liquid iron metal and sulfide than K. Dmet/sil for U, Th, and K increases with decreasing oxygen fugacity, while DUmet/sil and DKmet/sil increase when the metal is enriched and depleted in O or Si, respectively. We also used available data from the literature to constrain the concentrations of light elements (Si, S, O, and C) in Fe metal and sulfide. We calculated chemical compositions of Mercury’s core after core segregation, for a range of fO2 conditions during its differentiation. For example, if Mercury differentiated at IW-5.5, its core would contain 49 wt% Si, 0.02 wt% S, and negligible C. Also if core-mantle separation happened at a fO2 lower than IW-4, the bulk Mercury Fe/Si ratio is likely to be chondritic. We calculated concentrations of U, Th, and K in the Fe-rich core and possible sulfide layer of Mercury. Bulk Mercury K/U and K/Th were calculated taking all U, Th, and K reservoirs into account. Without any sulfide layer, or if Mercury’s core segregated at a higher fO2 than IW-4, bulk K/U and K/Th would be similar to those measured on the surface, confirming more elevated volatile K concentration than previously expected for Mercury. However, Mercury could fall on an overall volatile depletion trend where K/U increases with the heliocentric distance if core segregation occurred near IW-5.5 or more reduced conditions, and with a sulfide layer of at least 130 km thickness. At these conditions, the bulk Mercury K/Th ratio is close to Venus’s and Earth’s values. Since U and Th become more chalcophile with decreasing oxygen fugacity, to a higher extent than K, it is likely that at an fO2 close to, or lower than, IW-6 both K/U and K/Th become lower than values of the other terrestrial planets. Therefore, our results suggest that the elevated K/U and K/Th ratios of Mercury’s surface should not be exclusively interpreted as the result of a volatile enrichment in Mercury, but could also indicate a sequestration of more U and Th than K in a hidden iron sulfide reservoir, possibly a layer present between the mantle and core. Hence, Mercury could be more depleted in volatiles than Mars with a K concentration similar to or lower than the Earth’s and Venus’s, suggesting volatile depletion in the inner solar system. In addition, we show that the presence of a sulfide layer formed between IW-4 and IW-5.5 decreases the total radioactive heat production of Mercury by up to 30%.

Structures of Peptidic H‐wires at Mercury Surface: Molecular Dynamics Study

AbstractBiopolymer immobilization strategies, self‐assembly systems and adsorption phenomenon in general are crucial for the development of methods that work on the basis of the surface‐detection principle, including electrochemistry. A mechanistic view into the interaction of biopolymers with electrode surfaces is also important for studying fundamental and dynamic processes such as electron/proton transport. In this sense, the utilization of new approaches for investigating the interfacial behavior of immobilized biomolecular architectures is a permanent focus. Here we use a molecular dynamics (MD) approach to simulate the structural changes and metallic surface interactions of a model 21‐mer peptide of His (H) and Ala (A), A3(HA2)6, a peptidic proton wire (H‐wire). This H‐wire was previously proposed for the electrochemical study of proton transfer at mercury electrodes (Langmuir, 2018, 34, 6997). The rigid solid mercury mono‐atomic layer (α‐mercury lattice model) was used systematically in all our simulations. The calculations were performed in a simulation box with 1, 16 and 32 H‐wire strands attached covalently to the mercury layer via the thiol group of a cysteinamide residue appended to the H‐wire C‐terminus. The internal alpha‐helical configuration of H‐wires was maintained by the presence of 2,2,2‐trifluoroethanol. It was shown that both the surface density of H‐wires and the protonation state of His residues play a decisive role in the structural stability and orientation of the peptide to the surface, whereas the applied voltage only has a mild effect on it, especially in case of 16 and 32 H‐wire strand configurations. The MD simulations presented here could be used for the further investigation of other peptides at metallic surfaces and for electrochemical analyses of structural changes of surface‐attached peptides that depend on their protonation states and other external factors.

On low-Prandtl-number convection in an inclined layer of liquid mercury

This paper reports on a theoretical analysis of convection in an inclined layer of mercury, a common low-Prandtl-number fluid ($Pr=0.025$). The investigation is based on the standard Oberbeck–Boussinesq equations, which are explored as a function of the inclination angle $\unicode[STIX]{x1D6FE}$ and for Rayleigh numbers $R$ in the vicinity of the convection onset. Along with the conventional Galerkin methods to study convection rolls and their secondary instabilities, we employ direct numerical simulations for fluid layers with quite large aspect ratios. It turns out that, even for small inclination angles $\unicode[STIX]{x1D6FE}\lesssim 6^{\circ }$, the secondary instabilities of the basic rolls lead either to oscillatory three-dimensional patterns or to stationary ones, which appear alternately with increasing $\unicode[STIX]{x1D6FE}$. Due to the competition of these instabilities the patterns may show a complex dynamics.

Micro-invasive depth profile analysis by laser-induced breakdown spectroscopy (LIBS): the case of mercury layers on Sasanian coins

Calibration-Free Laser-Induced Breakdown Spectroscopy (LIBS) was used for depth-profile analysis of one Sasanian coin from the Kunsthistorisches Museum of Vienna, and to characterize the Hg layer covering its surface.

Monte Carlo Simulation of Photoelectric Characteristics of Mercury-Cadmium-Tellurium- Based Infrared Focal-Plane-Array Detectors

A mathematical model was developed to enable the Monte Carlo analysis of the charge-carrier diffusion process in the absorber layer of mercury–cadmium–tellurium (MCT) photovoltaic infrared focal-plane-array (IR FPA) detectors. Using this model, the distribution of local internal quantum efficiency $\eta $ of FPA elements over the FPA area was calculated. Afterward, the integral quantum efficiency of arbitrarily illuminated FPAs was determined via convolution of the obtained distribution of $\eta $ with illumination intensity. Following such calculations, some requirements to photoelectric properties of MCT material, and some suggestions on design optimization of FPA elements, allowing one to improve the sensitivity and spatial resolution of IR FPA detectors, were formulated.

Cytosine triphosphate-capped silver nanoparticles as a platform for visual and colorimetric determination of mercury(II) and chromium(III)

This work reports on a colorimetric platform for determination of chromium ions (Cr3+) and mercury ions (Hg2+) using silver nanoparticles (AgNPs) capped with cytosine triphosphate (CTP). The capped AgNPs were synthesized one-step by reduction of AgNO3 in the presence of CTP. It was found that such AgNPs aggregate in the presence of Cr3+. This results in a decrease in the intensity of the surface plasmon resonance (SPR) band at 390 nm and the formation of a new red-shifted band at 510 nm, and consequently a color change from yellow to red. Different from the Cr3+-induced aggregation of AgNPs, exposure to Hg2+ causes the formation of a mercury layer around the surface of the AgNPs. This, in turn, causes the SPR absorption of the AgNPs to decrease and to undergo a slight blue shift, and this results in a fading of the yellow color. The findings are the basis of developing a new method for quantification of either Cr3+ or Hg2+, with detection limits of 6.25 μM for Cr3+ and of 0.125 μM for Hg2+, respectively. The method was applied to the determination of the two ions in spiked drinking water and lake water samples, and recoveries ranged from 94.5% to 101.3% for Cr3+, and from 96% to 108% for Hg2+, which is satisfactory for quantitative assays performed in water samples.

Determination of heavy metals in soil and biomass by the application of potentiometric stripping analysis

In this paper the determination of lead, cadmium and zinc in soil and biomass was performed using potentiometric stripping analysis (PSA). In order to establish the optimal experimental conditions for PSA of Pb, Cd and Zn, the influence of pH value, time of metals extraction, stirring rate of the solution and the thickness of the mercury layer, as the working electrode, was investigated. The influence of mentioned parameters was tested for individual and simultaneous metals determination. The achieved limits of determination of single ions were for: lead 22.5 μg dm-3, cadmium 16.2 μg dm-3 and zinc 18.8 μg dm-3. The obtained results deviated from the expected for 1.1%, 1.9% and 1.8%, for lead, cadmium and zinc, respectively. For simultaneous determination, the method is tested using the ions contents as follows: 45.0 μg dm-3 for lead, 32.5 μg dm-3 for cadmium and 37.5 μg dm-3 for zinc. The relative errors for simultaneous determination were: 4.6% for lead, 1.9% for cadmium and 1.9% for zinc. For the established optimal conditions, except for lead, deviations did not exceed ±2%. It is shown that potentiometric stripping analysis is usable for individual and simultaneous determination of lead, cadmium and zinc in soil and biomass.

Development and application of potentiometric stripping analysis

This paper focuses on the voltammetric determination of lead, cadmium and zinc in water. Two ways of determining were investigated: individually and all three metals simultaneously. The experiments were performed using the Potentiometric Stripping Analysis (PSA). Determination of metals in real samples was preceded by preliminary tests. Preliminary investigations were performed in order to determine the optimal conditions of measurement. It was concluded that the process of determining was for most part influenced by: pH, time of metals extraction, stirring rate of the solution and the thickness of the mercury layer on the working electrode. The smallest concentrations of metals which can be determined using this method are: for lead 22.48 μg dm-3, for cadmium 16.23 μg dm-3 and for zinc 18.75 μg dm-3. The obtained results deviated from the actual 1.12% for lead, 1.91% for cadmium and 1.81% for zinc. All tests (individually and simultaneously) were conducted from model solution with concentration as follows: 44.96 μg dm-3 for lead, 32.47 μg dm-3 for cadmium and 37.50 μg dm-3 for zinc. The results of individual measurements deviated by 1.02% lead, 1.90% for cadmium and 1.89% for zinc. Simultaneously the contents were lower than real for: -4.58% for lead, cadmium for -1.91% and -1.89% for zinc. For the conditions determined, except for lead, deviations did not exceed ±2% . This indicates that Potentiometric Stripping Analysis is a good way of individual and simultaneous determination of lead, cadmium and zinc and for determination of their concentrations in water (river and groundwater).

Probing liquid mirror surface quality using the charge coupled device triangulation technique

In the framework of the 4-m International Liquid Mirror Telescope project, we have developed an innovative technique to assess the optical quality of liquid mirrors, whose optical quality may be affected by the propagation of wavelets over the mercury layer. We present a method based upon the reflection of a laser beam over the surface and present the mathematical modeling as well as preliminary results obtained from laboratory measurements.

A nanoscopic insight into electrocatalytic origins of the mercury monolayer carbon fiber electrode depicted by fast cyclic voltammetry

With the aim to unveil the origins of the electrocatalytic properties of the low-dimensional mercury monolayer carbon fiber electrode (MMCFE) the study of the cathodic and anodic background currents, specified by the proton reduction and the hydrogen oxidation, on bare and covered by a mercury monolayer carbon fiber electrode, in a wide domain of potentials and pH was carried out by means of fast (v=0.1–20,000Vs−1) cyclic voltammetry.It was found a large difference between the electric charges passed during the negative- and the positive-going semi-cycles controlled by the magnitude of the applied negative potential (E), which abruptly increases when E<−1.4V(SHE), specifying appearance of an unpaired anodic peak around E=0.7V (attributed to the electrooxidation of ‘absorbed’ atomic hydrogen (H0)) and reaches a maximum at E<−1.8V followed by the appearance of the second anodic peak around E=−1.9V (attributed to the oxidation of H0 diffused into the bulk electrolyte).The significant excess (>103) of the anodic electric charge, caused by the electrooxidation of H0, is explained by its homogeneous (nonfaradaic) generation by conversion of the field emitted electron.The Fowler–Nordheim plot denotes the source of electron emission as an open nanopore (with a width of 3–4Å) formed between two external graphene sheets of the carbon fiber, where the electric field attains a maximal value of nearly 3×107Vcm−1.The electrolytic deposition of a single metal atom, matching the open nanopore dimension increases the electron emission by more than two orders on MMCFE, fact explained by formation there of the Schottky nanojunction between the semiconducting carbon fiber and the metallic mercury layer.

A shallow water model for magnetohydrodynamic flows with turbulent Hartmann layers

We establish a shallow water model for flows of electrically conducting fluids in homogeneous static magnetic fields that are confined between two parallel planes where turbulent Hartmann layers are present. This is achieved by modelling the wall shear stress in these layers using Prandtl’s mixing length model, as did by Alboussière and Lingwood [Phys. Fluids 12(6), 1535 (2000)]. The idea for this new model arose from the failure of previous shallow water models that assumed a laminar Hartmann layer to recover the correct amount of dissipation found in some regimes of the MATUR experiment. This experiment, conducted by Messadek and Moreau [J. Fluid Mech. 456, 137 (2002)], consisted of a thin layer of mercury electrically driven in differential rotation in a transverse magnetic field. Numerical simulations of our new model in the configuration of this experiment allowed us to recover experimental values of both the global angular momentum and the local velocity up to a few percent when the Hartmann layer was in a sufficiently well developed turbulent state. We thus provide an evidence that the unexplained level of dissipation observed in MATUR in these specific regimes was caused by turbulence in the Hartmann layers. A parametric analysis of the flow, made possible by the simplicity of our model, also revealed that turbulent friction in the Hartmann layer prevented quasi-2D turbulence from becoming more intense and limited the size of the large scales.

Gold nanoparticles generated through “green route” bind Hg2+ with a concomitant blue shift in plasmon absorption peak

We discuss here a quick, simple, economic and ecofriendly method through a completely green route for the selective detection of Hg(2+) in aqueous samples. Here we exploited the ability of chitosan to generate gold nanoparticles and subsequently to act as a stabilizer for the formed nanoparticles. When chitosan stabilized gold nanoparticles (CH-Au NPs) are interacted with Hg(2+) a blue shift for its localized surface plasmon resonance absorbance (LSPR) band is observed. The blue shift is reasoned to be due to the formation of a thin layer of mercury over gold. A concentration as low as 0.01 ppm to a maximum of 100 ppm Hg(2+) can be detected based on this blue shift of the CH-Au NPs. While all other reported methods demand complex reaction steps and costly chemicals, the method we reported here is a simple, rapid and selective approach for the detection of Hg(2+). Our results also show that the CH-Au NPs have excellent selectivity to Hg(2+) over common cations namely, Pb(2+), Cd(2+), Mn(2+), Fe(2+), Ag(1+), Ce(4+), Ni(2+), and Cu(2+).

Structure of the surface layer of mercury and adhesion of Langmuir monolayers on it

A model crystalline approximant of the surface layer (SL) structure of liquid mercury is formed using the algorithm, previously applied to form a crystalline approximant of the SL structure of water, the experimental data on the SL structure of mercury, and the stereochemical data for Hg atoms in the α-Hg crystalline phase and bulk liquid mercury. The correspondence of the metrics of the crystalline approximant proposed for the SL structure of mercury and Langmuir monolayers composed of organic molecules with hydrocarbon tails and different hydrophilic groups on liquid mercury to the position of molecules along mercury SL is shown.

Rapid determination of zeptomole quantities of Pb 2+ with the mercury monolayer carbon fiber electrode

This work describes and studies a process for electrolytic deposition of a mercury monolayer on a carbon fiber electrode. Exceptional sensitivity for the determination of Pb 2+ is demonstrated when the mercury-monolayer-on-carbon electrode (MMCFE) is used with fast ( v > 1 kV/s) anodic stripping voltammetry. Investigation of the nature of the analytical signal revealed that the high sensitivity is due to ionization of Pb atoms in the mercury layer, which catalyzes the oxidation of atomic hydrogen adsorbed at the Hg layer. For a 1 s preconcentration time at a cylinder electrode ( A = 1.1 × 10 −3 cm 2), the calculated detection limit (3 std. dev. of baseline noise) is 80 fM, corresponding to ca. 1 zeptomole of Pb.

From bulk materials to nanoparticles using a one-step electrochemical method

This paper describes an electrochemical method which permits us to transform solid metals(cobalt, iron or nickel) into nanoparticles. An electrolysis cell is made, the anode being ametal bar and the cathode a mercury layer. Magnetic nanoparticles are obtained inone step by electroreduction of mercury. Electrolysis is performed in an aqueousmedium at pH above 6 in order to avoid the reduction of protons. The magneticnanoparticles obtained are kept in mercury and can be recovered in an organicsolvent.

Development of Hg-Au Microelectrode for Measuring O 2, Mn 2+, Fe 2+ and S 2− in Marine Sediment Pore Water

Hg-Au voltammetric microelectrodes were developed by electroplating mercury membrane onto Au microelectrodes. The Au electrode was constructed by sealing one end of a 100-μm diameter gold wire within a glass capillary using epoxy and attaching the other end to a silver wire for electrical contact using conductive epoxy. The silver wire was fastened to the top of the glass tube using epoxy again. The tip of the electrode was ground flat and smooth gradually from coarse to fine grain under a micropolisher. It was then washed in 1 M HNO 3 solution and in deionized water under supersonic action. The electrode was electroplated with a layer of mercury within 0.1 M Hg(NO 3) 2/0.03 M HNO 3 electrolyte at a potential of −0.10 V versus saturated calomel electrode (SCE) for 5 min. By adopting three-electrode cell and square wave voltammetry, Hg-Au microelectrode can measure dissolved oxygen, Mn 2+, Fe 2+ and sulfide during a single potential scan from −0.10V to −1.75V versus saturated calomel electrode (SCE). The experimental results indicated that the microelectrode had the sensitivity and detection limit of 0.16 nA μM −1, 6 μM for dissolved oxygen; 0.35 nA μM −1, 3 μM for Mn 2+; 0.22 nA μM −1, 5 μM for Fe 2+, and 34 nA μM −1, 0.03 μM for sulfide. It was found that the microelectrode exhibited good reproducibility with an error below 3% after measuring 15 sediment samples consecutively.

Image Quality of Liquid‐Mirror Telescopes

ABSTRACTThe quality of astronomical images obtained with the 3 m liquid‐mirror telescope (LMT) of the NASA Orbital Debris Observatory (NODO) and with the University of British Columbia 6 m Large Zenith Telescope (LZT) is assessed and compared to that of conventional instruments. Analysis of star images in long‐exposure drift‐scan data indicates that the profile of the image core is primarily set by atmospheric turbulence. Defocused star images reveal the presence of low‐amplitude waves on the surface of the mercury, also seen in laboratory tests. The effect of these waves is to diffract light into the wings of the point‐spread function. Analysis of the intensity profiles of stellar images can therefore probe the structure of the mirror surface on scales smaller than the atmospheric coherence length, which is about an order of magnitude larger that the characteristic wavelengths of the surface waves. It is found that the rms surface height error produced by these waves was approximately 37 nm for the NODO LMT. Improvements to the rotational speed stability of liquid mirrors, reduction of the thickness of the mercury layer, and use of a protective Mylar cover have allowed the LZT to reduce this source of error to approximately 9 nm rms, thereby achieving an image quality approaching that of conventional telescopes.

Early geodynamo work

Regarding the February cover article on the quest for a laboratory geodynamo (Physics Today, February 2006, page 13), it is important, as Isaac Newton said, to “stand on the shoulders of giants” as we advance our understanding. Unfortunately, the present generation often fails to do so. Consider, for example, the Bullard–Rikitake dynamo theory, which explains not only the axial field but also its periodic spontaneous reversal, as observed in ocean-bottom cores. Here is the background:In the early 1950s, Edward Bullard and a student of his named Rikitake built a geodynamo at the University of Newcastle upon Tyne in the UK. It consisted of two counter-rotating iron cylinders about two meters in diameter, connected electrically by an equatorial layer of mercury. It generated an axial magnetic field that spontaneously reversed its direction every 20 minutes, as Earth’s field is known to do every 10 000 years or so.The actual geodynamo has yet another peculiar and unexplained property: It is substantially off-center by about 10% of Earth’s diameter. Earth’s field is about 0.6 gauss in Siberia, and about 0.1 gauss in the diametrically opposite region in the southern Atlantic Ocean, as I pointed out in a paper presented in the 1950s at a symposium at Newcastle. This asymmetry is considerably harder to explain than the field generation itself or its periodic reversals.I mention this for readers who may be interested in joining this fascinating field of experimental geophysics. © 2006 American Institute of Physics.