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Sensitive and robus...
Sensitive and robust electrophoretic NMR : Instrumentation and experiments
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- Hallberg, Fredrik (författare)
- KTH,Fysikalisk kemi
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- Furo, Istvan (författare)
- KTH,Fysikalisk kemi
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- Yushmanov, Pavel V. (författare)
- KTH,Fysikalisk kemi
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- Stilbs, Peter (författare)
- KTH,Fysikalisk kemi
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(creator_code:org_t)
- Elsevier BV, 2008
- 2008
- Engelska.
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Ingår i: Journal of magnetic resonance. - : Elsevier BV. - 1090-7807 .- 1096-0856. ; 192:1, s. 69-77
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Although simple as a concept, electrophoretic NMR (eNMR) has so far failed to find wider application. Problems encountered are mainly due to disturbing and partly irreproducible convection-like bulk flow effects from both electro-osmosis and thermal convection. Additionally, bubble formation at the electrodes and rf noise pickup has constrained the typical sample geometry to U-tube-like arrangements with a small filling factor and a low resulting NMR sensitivity. Furthermore, the sign of the electrophoretic mobility cancels out in U-tube geometries. We present here a new electrophoretic sample cell based on a vertically placed conventional NMR sample tube with bubble-suppressing palladium metal as electrode material. A suitable radiofrequency filter design prevents noise pickup by the NMR sample coil from the high-voltage leads which extend into the sensitive sample volume. Hence, the obtained signal-to-noise ratio of this cell is one order of magnitude higher than that of our previous U-tube cells. Permitted by the retention of the sign of the displacement-related signal phase in the new cell design, an experimental approach is described where bulk flow effects by electro-osmosis and/or thermal convection are compensated through parallel monitoring of a reference signal from a non-charged species in the sample. This approach, together with a CPMG-like pulse train scheme provides a superior first-order cancellation of non-electrophoretic bulk flow effects.
Nyckelord
- electrophoretic NMR
- eNMR
- method
- convection
- electro-osmosis
- suppression
- electrophoresis
- NUCLEAR-MAGNETIC-RESONANCE
- CYLINDRICAL FLUID LAYER
- SURFACTANT SYSTEMS
- THERMOCONVECTIVE INSTABILITY
- TRANSFERENCE NUMBERS
- EFFECTIVE CHARGE
- MOBILITY
- CAPILLARY
- POLYMER
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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