Neutron reflection and the thermodynamics of the air-water interface
By means of isotopic substitution, measurements of the neutron reflectivity (NR) from a flat water surface generally give model independent measurements of the amount of a chosen solute at the surface irrespective of whether the layer is a mixture or whether there is any aggregation in the bulk solu...
| Main Authors: | , |
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| Format: | Journal article |
| Language: | English |
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Royal Society of Chemistry
2022
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| _version_ | 1797109197540687872 |
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| author | Penfold, J Thomas, RK |
| author_facet | Penfold, J Thomas, RK |
| author_sort | Penfold, J |
| collection | OXFORD |
| description | By means of isotopic substitution, measurements of the neutron reflectivity (NR) from a flat water surface generally give model independent measurements of the amount of a chosen solute at the surface irrespective of whether the layer is a mixture or whether there is any aggregation in the bulk solution. Previously, adsorption at air–water interfaces has been determined by applying the Gibbs equation to surface tension (ST) measurements, which requires assumptions about the composition of the surface and about the activity of the solute in the bulk, which, in turn, means that in practice the surface is assumed to consist of the pure solute or of a mixture of pure solutes, and that the activity of the solute in the bulk solution is known. The use of NR in combination with ST-Gibbs measurements makes it possible to (i) avoid these assumptions and hence understand several patterns of ST behaviour previously considered to be anomalous and (ii) to start to analyse quantitatively the behaviour of mixed surfactants both below and above the critical micelle concentration. These two developments in our understanding of the thermodynamics of the air–water interface are described with recent examples. |
| first_indexed | 2024-03-07T07:37:00Z |
| format | Journal article |
| id | oxford-uuid:ca8247e1-70f3-4561-b079-402aa8c27ae6 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:37:00Z |
| publishDate | 2022 |
| publisher | Royal Society of Chemistry |
| record_format | dspace |
| spelling | oxford-uuid:ca8247e1-70f3-4561-b079-402aa8c27ae62023-03-17T14:15:57ZNeutron reflection and the thermodynamics of the air-water interfaceJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:ca8247e1-70f3-4561-b079-402aa8c27ae6EnglishSymplectic ElementsRoyal Society of Chemistry2022Penfold, JThomas, RKBy means of isotopic substitution, measurements of the neutron reflectivity (NR) from a flat water surface generally give model independent measurements of the amount of a chosen solute at the surface irrespective of whether the layer is a mixture or whether there is any aggregation in the bulk solution. Previously, adsorption at air–water interfaces has been determined by applying the Gibbs equation to surface tension (ST) measurements, which requires assumptions about the composition of the surface and about the activity of the solute in the bulk, which, in turn, means that in practice the surface is assumed to consist of the pure solute or of a mixture of pure solutes, and that the activity of the solute in the bulk solution is known. The use of NR in combination with ST-Gibbs measurements makes it possible to (i) avoid these assumptions and hence understand several patterns of ST behaviour previously considered to be anomalous and (ii) to start to analyse quantitatively the behaviour of mixed surfactants both below and above the critical micelle concentration. These two developments in our understanding of the thermodynamics of the air–water interface are described with recent examples. |
| spellingShingle | Penfold, J Thomas, RK Neutron reflection and the thermodynamics of the air-water interface |
| title | Neutron reflection and the thermodynamics of the air-water interface |
| title_full | Neutron reflection and the thermodynamics of the air-water interface |
| title_fullStr | Neutron reflection and the thermodynamics of the air-water interface |
| title_full_unstemmed | Neutron reflection and the thermodynamics of the air-water interface |
| title_short | Neutron reflection and the thermodynamics of the air-water interface |
| title_sort | neutron reflection and the thermodynamics of the air water interface |
| work_keys_str_mv | AT penfoldj neutronreflectionandthethermodynamicsoftheairwaterinterface AT thomasrk neutronreflectionandthethermodynamicsoftheairwaterinterface |