Optical spectroscopy of surface states on NaCl and KCl crystals and its relation to contact charging

Ernst, L.

doi:10.1016/0038-1098(76)91339-9

Cited by 28 publications

(4 citation statements)

References 6 publications

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“…The simple arrangement depicted schematically in Fig. 3 has been used [17] to measure the C C of single crystals.…”

Section: A) the Measurement Of The CC Of Single Crystalsmentioning

confidence: 99%

“…It was established that the charges transferred by contacting are localised on the surface of the crystals, i.e. surface states are involved: the CC consists of electron transfer from filled to empty surface states [17]. The total charge density attainable after many contacts is in general in the range of lo-'' to lo-'' C cm-', corresponding to lo7 to lo9 e cm-'.…”

Section: B) CC Of Nacl and Kci Crystals With "Pure" Cleavage Facesmentioning

confidence: 99%

“…It is suspected that they may be generated in the course of crystal cleaving [19]. The density and the energy distribution of these extrinsic surface states show variations from probe to probe [17,19] and even in the case of different probes cleaved from the same crystal, the CC may vary. Usually NaCl and KCI are charged positively by contacting with gold for example, because of the relatively large work function of the latter [17], however, there is no rule which would predict in general the sign of the CC of NaCl versus KCl.…”

Section: B) CC Of Nacl and Kci Crystals With "Pure" Cleavage Facesmentioning

confidence: 99%

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The Surface‐vacancy Bonded H₂O Molecule on an Alkali Halide (100) Crystal Face and a Model of the Stimulated Contact Charging in the Electrostatic Potash Salt Processing

Ernst

1989

Ber Bunsenges Phys Chem

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In the electrostatic processing of raw potash salt the mutual contact charging of its components is an important step. — The contact charging may be component‐selectively stimulated by, mainly, organic acid additives, added to the salt in concentrations of 10 ppm‐s under conditions of well‐defined relative humidity of the ambient air. This technology was developed purely empirically and the mechanism of the stimulated contact charging is as yet unknown. — In the present work some light will be shed onto this mechanism. Results for the contact charging of NaCl versus KCl and versus some metals, stimulated by one of the most frequently used additives, salicylic acid, have been considered. Based on photoemission data from water adsorbed on alkali halide (100) crystal faces, it is suggested that H2O molecules, bonded in surface cation vacancies may have a role in the additive‐induced stimulation of the contact charging. On a NaCl(100) face they may capture the proton from the salicylic acid molecules forming vacancy‐trapped H3O+ ions, with their charge screened by the lattice and quasi‐free salicylate ions. The ionization energy of the latter is so small that their surplus electron may be injected readily into any of the possible contact partners. — The model describes the essential features of the contact charging stimulation of the electrostatic salt processing. The component‐selectivity is as yet not understood, however, the model supplies useful hints related to its possible causes.

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“…The simple arrangement depicted schematically in Fig. 3 has been used [17] to measure the C C of single crystals.…”

Section: A) the Measurement Of The CC Of Single Crystalsmentioning

confidence: 99%

Section: B) CC Of Nacl and Kci Crystals With "Pure" Cleavage Facesmentioning

confidence: 99%

Section: B) CC Of Nacl and Kci Crystals With "Pure" Cleavage Facesmentioning

confidence: 99%

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The Surface‐vacancy Bonded H₂O Molecule on an Alkali Halide (100) Crystal Face and a Model of the Stimulated Contact Charging in the Electrostatic Potash Salt Processing

Ernst

1989

Ber Bunsenges Phys Chem

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“…Which properties of materials or material pairs can be quantitatively ascribed to the tribocharge and explain the triboelectric ranking? To address these concerns, various plausible models for electron transfer have been suggested, such as the spatial charge redistribution model, ,, the surface state model, − the effective work function model, − and the interface potential barrier model. , However, none of these models comprehensively resolved the above questions due to various difficulties related to high-quality sample preparation to exclude mixed extrinsic effects and a lack of comprehensive coordination between quantitative calculations and measurements.…”

mentioning

confidence: 99%

Triboelectrification: Backflow and Stuck Charges Are Key

Lim

Han

et al. 2021

ACS Energy Lett.

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To understand the most intrinsic mechanism of triboelectrification (TE), a straightforward framework of TE between metal and single-crystal dielectrics is designed by utilizing both experiments and first-principles calculations. Various theoretical models on charge transfer are examined with first-principles calculations. Interestingly, the measured charge density shows a proportional relation with the interface barrier, which is in contrast with the previous theories. On the basis of the results, a backflow-stuck charge model is proposed where the charge density is determined by the amount of backflow and the remaining stuck charges at separation. We also validated this model by comparing the theoretically predicted barrier and the extracted barrier from the temperature-dependent triboelectrification. The results soundly support that backflow-stuck charges determine the charge density at TE, where the interface barrier plays a key role. The model provides a new perspective of the charge transfer mechanism on the TE and can be generally applied to TE of conventional materials.

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Photoelectron Emission from Rhodamine B Adsorbed on Various Substrates

Ernst¹

1983

Ber Bunsenges Phys Chem

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The quantum yield of photoelectrons, emitted from rhodamine B layers, which were adsorbed on cleaved faces of ionic crystals and on polished faces of amorphous quartz, has served to estimate the effective densities of occupied dye states in a small energy range below the vacuum level. For NaCl(100), RbCl(100), and calcite (1010) substrates the energy distributions of these states are very similar. If the substrate is amorphous quartz, the density of dye states in the investigated energy range is negligible in comparison to that on the ionic crystals. Assumptions are made concerning the possible origin of the relatively high density of dye states generated on ionic crystals.

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Optical spectroscopy of surface states on NaCl and KCl crystals and its relation to contact charging

Cited by 28 publications

References 6 publications

The Surface‐vacancy Bonded H₂O Molecule on an Alkali Halide (100) Crystal Face and a Model of the Stimulated Contact Charging in the Electrostatic Potash Salt Processing

The Surface‐vacancy Bonded H₂O Molecule on an Alkali Halide (100) Crystal Face and a Model of the Stimulated Contact Charging in the Electrostatic Potash Salt Processing

Triboelectrification: Backflow and Stuck Charges Are Key

Photoelectron Emission from Rhodamine B Adsorbed on Various Substrates

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Optical spectroscopy of surface states on NaCl and KCl crystals and its relation to contact charging

Cited by 28 publications

References 6 publications

The Surface‐vacancy Bonded H2O Molecule on an Alkali Halide (100) Crystal Face and a Model of the Stimulated Contact Charging in the Electrostatic Potash Salt Processing

The Surface‐vacancy Bonded H2O Molecule on an Alkali Halide (100) Crystal Face and a Model of the Stimulated Contact Charging in the Electrostatic Potash Salt Processing

Triboelectrification: Backflow and Stuck Charges Are Key

Photoelectron Emission from Rhodamine B Adsorbed on Various Substrates

Contact Info

Product

Resources

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The Surface‐vacancy Bonded H₂O Molecule on an Alkali Halide (100) Crystal Face and a Model of the Stimulated Contact Charging in the Electrostatic Potash Salt Processing

The Surface‐vacancy Bonded H₂O Molecule on an Alkali Halide (100) Crystal Face and a Model of the Stimulated Contact Charging in the Electrostatic Potash Salt Processing