Selective observation of concentration gradients by the laser beam deflection sensor applied to in situ electrochemical studies.  A novel approach

Pawliszyn, Janusz; Weber, M.; Dignam, M. J.; Park, Su Moon.

doi:10.1021/ac00292a059

Cited by 43 publications

(7 citation statements)

References 36 publications

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“…The concentration gradient-induced OBD signal θ is expressed as follows 22,23 where l , n , ∂n / ∂c , and ∂c / ∂z are path length of the probe beam, refractive index of the organic solvent, concentration-dependent coefficient of the refractive index, and the concentration gradient, respectively. In a certain range of concentration, ∂n / ∂c is usually approximated as a constant. − Then, eq 1 indicates the deflection signal is proportional to ∂n / ∂z .…”

Section: Resultsmentioning

confidence: 99%

“…The optical beam deflection (OBD) method, , based on the mirage effect, is a well-known noncontact and noninvasive analytical method, which can be applied to a physical or chemical system where a refractive index gradient is produced. Since the refractive index of a substance is a function of temperature, it has been used for probing a temperature gradient, which is generated by either the nonradiative relaxation of photon energy absorbed by molecules , or reaction heat released from a chemical reaction. − It also has been used for probing a concentration gradient generated in an electrode/solution interface, − flow injection systems, − and capillary electrophoresis. , The concentration gradient-induced OBD method has been used for evaluating the diffusion coefficients of some electrolytes in aqueous solutions. , The transient signal of the concentration gradient-induced OBD has been used for separating large and small species, such as sucrose and poly(acrylic acid), since they have different diffusion coefficients …”

Section: Introductionmentioning

confidence: 99%

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Noncontact and Noninvasive Monitoring of Gas Diffusion from Aqueous Solution to Aprotic Solvent Using the Optical Beam Deflection Method

Morikawa

Uchiyama

et al. 1997

J. Phys. Chem. B

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The optical beam deflection method has been applied to noncontact and noninvasive monitoring and analyzing of gas diffusion process from an aqueous solution into an aprotic solvent. Oxygen and carbon dioxide, which are in situ generated by chemical reactions in aqueous solutions above aprotic solvents, have been used as model gases. Both the model gas and the reaction heat diffuse from the aqueous solution to the aprotic solvent and thus generate a concentration gradient and a temperature gradient. Both the concentration gradient and the temperature gradient induce optical beam deflections. Since the thermal diffusion is faster than the mass diffusion, the reaction heat-induced beam deflection signal appears earlier than the concentration gradientinduced one. A simple diffusion model has been used for analyzing the diffusion process. The diffusion coefficient of the model gas in the aprotic solvent can be estimated simply from the beam deflection signal. The diffusion coefficients of O 2 in CCl 4 , CH 2 Cl 2 , C 2 H 4 Cl 2 , and CS 2 have been obtained. The method is expected to be particularly useful for those diffusion processes where other methods are not applicable.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Noncontact and Noninvasive Monitoring of Gas Diffusion from Aqueous Solution to Aprotic Solvent Using the Optical Beam Deflection Method

Morikawa

Uchiyama

et al. 1997

J. Phys. Chem. B

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“…More popular methods such as probebeam deflection in its nonspectrophotometric form [177,178] are now used to profile the diffusion layer, and in conjunction with electrochemical quartz crystal microbalance (EQCM) measurements, are used to monitor the diffusion layer ingress and egress of ions, particularly protons. Further details can be found in Chapter 2.7 in this volume.…”

Section: Glancing Incidence Reflection Near-parallel or Parallel Refmentioning

confidence: 99%

Spectroelectrochemistry: In s itu UV ‐visible Spectroscopy

Crayston

2003

Encyclopedia of Electrochemistry

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The sections in this article are Introduction and Principles Introductory Remarks Theory and Techniques: Steady State Measurement Cell Transmission for a Simple Electron Transfer Reaction: Determination of E and n Effect of Follow‐up Reactions in OTTLE Cells Theory and Techniques: Kinetic Measurements Chronoabsorptometry Instrumentation for Chronoabsorptometry Slow Heterogeneous Kinetics Effect of Follow‐up Reactions Derivative Cyclic Voltabsorptometry ( DCVA ) Galvanostatic Conditions Adsorption Cell Geometries, Design, Techniques, and Instrumentation General Considerations Transmission under Thin‐layer Conditions: OTTLEs and Flow‐cells Variations on and Alternatives to the Basic OTTLE Design OTTLE Cells Intended for Both UV ‐visible and FTIR Use OTTLE Cell Electrochemical and Spectroscopic Response Semi‐infinite Cells: Optically Transparent Electrodes ( OTEs ) Reflection from Electrodes and Liquid–Liquid Interfaces Glancing Incidence Reflection, Near‐parallel or Parallel Reflection, and Diffraction Liquid–Liquid Interface and Attenuated Total Reflection Long Optical Path‐length Thin‐layer Cell ( LOPTLC ) Forced Convection, RDE and Channel Flow UV ‐vis Combined with Other Spectroscopic Techniques Applications Solution Studies of Inorganic Species Solution Studies of Organic Species Molten Salts Spectroelectrochemistry Studies of Species of Biological Interest Inorganic Thin Films and Modified Electrodes Conducting Polymers and Oligomer Models Conclusions

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“…7 In this regard electrochemical techniques offer accurate measurements of concentration profiles generated at electrodes however only under conditions where a secondary electrode can be adequately positioned and scanned. 8 Optical probing methods, such as absorption, 9 refractive index, 10 IR, 11 or fluorescence 12 spectroscopies, circumvent this spatial restriction and thus may examine active areas inside transparent porous supports. However, these methods are typically restricted to analyte solutions whose concentrations are above a few μM.…”

Section: ■ Introductionmentioning

confidence: 99%

Counting Single Redox Turnovers: Fluorogenic Antioxidant Conversion and Mass Transport Visualization via Single Molecule Spectroelectrochemistry

Godin

Cosa

2016

J. Phys. Chem. C

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We report herein the use of single molecule spectroelectrochemistry (SMS-EC) to optically detect electrochemicallyactivated individual molecules of the redox active, tocopherol-like fluorogenic probe H2B-PMHC. Single molecule detection combined with a fluorescence burst frequency analysis is shown to provide a most sensitive method to monitor sub-nanomolar concentrations of the electrochemically-activated probe. By measuring changes in activated probe concentration over time and distance from a planar electrode, mass transport characteristics of a prototype infinite planar electrode system are retrieved as a showcase study. We show that fluorescence activation may be achieved under both oxidative (direct oxidation of H2B-PMHC) and reductive (via O2 •-production) conditions. Our results conducted in organic solvents broaden the scope of electrochemical reactions that can be studied by SMS-EC. The methodology we describe may potentially aid the study of mass transport in systems with complex electrode geometries or hampered diffusion.

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Selective observation of concentration gradients by the laser beam deflection sensor applied to in situ electrochemical studies. A novel approach

Cited by 43 publications

References 36 publications

Noncontact and Noninvasive Monitoring of Gas Diffusion from Aqueous Solution to Aprotic Solvent Using the Optical Beam Deflection Method

Noncontact and Noninvasive Monitoring of Gas Diffusion from Aqueous Solution to Aprotic Solvent Using the Optical Beam Deflection Method

Spectroelectrochemistry: In s itu UV ‐visible Spectroscopy

Counting Single Redox Turnovers: Fluorogenic Antioxidant Conversion and Mass Transport Visualization via Single Molecule Spectroelectrochemistry

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