Pulsed Laser Depassivation of Metallic Electrodes in Aqueous Corrosive Media

Oltra, R.; Indrianjafy, G. M.; Boquillon, J.P.

doi:10.1051/jp4:19917206

Cited by 4 publications

(7 citation statements)

References 9 publications

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“…We propose that thermoelastic stresses [22,37] are induced in the platinum electrode by absorption of laser energy together with localized heating and solution convection currents which in turn maintain a diffusion layer at the electrode surface and facilitate a steady mass-transport limited current. Values of d, calculated assuming D has its bulk value, as a function of laser intensity are given in Table 2 can can be seen to decrease as the laser-induced thermal convection increases.…”

Section: Mass Transport Modelmentioning

confidence: 99%

Laser Activated Voltammetry: Mass Transport, Surface Effects and Analytical Applications

et al. 1999

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The voltammetry of various well-characterized aqueous and nonaqueous electrochemical systems has been studied at platinum and gold disk electrodes under illumination from a 10 Hz pulsed Nd:YAG laser frequency doubled to operate at 532 nm. A simple Nernst diffusion layer model is established to quantify the slight enhancement in mass transport observed as a function of laser intensity in the thermoelastic region where light energy absorbed by the metal is insuf®cient to cause localized melting or vaporization but does lead to a partial thinning of the diffusion layer thickness through surface heatingavibration. This leads to sigmoidal shaped voltammograms whilst maintaining a clean, reproducible electrode surface. Above the ablation threshold, the minimum laser intensity required to cause electrode damage, atomic force microscopy (AFM) is used to probe the nature of the surface damage and its relationship to the laser intensity. The Nernst-diffusion model is veri®ed by means of potential step chronoamperometric measurements in water and acetonitrile where good agreement with theory is seen for transport across a diffusion layer of a thickness corresponding to that inferred from steady-state voltammetry. Applications of the laser activation technique are illustrated by three systems found to be passivating in aqueous media; the two electron reduction of toluidine blue dye, iodide oxidation and the oxidation of ferrocyanide in the presence of the blood protein, ®brinogen. In all cases clean, reproducible and quantitative voltammetry is seen in contrast to that observed in the absence of laser activation, demonstrating the excellent surfacecleaning effects of LAV.

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Section: Mass Transport Modelmentioning

confidence: 99%

Laser Activated Voltammetry: Mass Transport, Surface Effects and Analytical Applications

et al. 1999

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“…The practical relevance of explosive liquid evaporation in steam laser cleaning and other technologically important areas, such as laser surgery [9], laser chemistry [10,11], and localized depassivation of metallic surfaces [12,13], has motivated research in the bubble nucleation and pressure generation processes induced by pulsed laser heating of a liquid-solid interface. Initial studies had been performed on thin liquid films by using an optical transmission probe [14], which provides useful information on temperature transients and "explosion" thresholds.…”

mentioning

confidence: 99%

Bubble nucleation and pressure generation during laser cleaning of surfaces

Yavaş¹,

Schilling²,

Bischof³

et al. 1997

Applied Physics A: Materials Science & Processing

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Abstract. Bubble nucleation and growth dynamics, on a nanosecond time scale, induced by pulsed laser heating of a liquid-solid interface are studied experimentally. A surface-plasmon probe is implemented as a novel, highly sensitive method for the study of submicroscopic bubbles, providing accurate information on the nucleation thresholds, growth velocities, and transient pressure generation by rapid bubble growth. Owing to the higher sensitivity of the surface plasmon probe to small bubbles, it is demonstrated that bubble nucleation sets in at a lower liquid superheating than previously determined with the use of optical reflectance or piezoelectric transducer measurements. A comparison of experimentally determined bubble growth velocities with computational results confirms that bubble growth is governed by the heat transfer from the solid surface into the liquid. Reconstructed surface plasmon resonance curves from transient signals are used to estimate the fractional volume and number density of bubbles in the superheated liquid layer. Further, a surface plasmon probe is utilized for the absolute measurement of bubble-growthinduced pressure amplitudes on a nanosecond time scale. The measurements yield peak pressure amplitudes in the range of ∼ 1-5 MPa with a pressure pulse width of ∼ 40 ns. Additionally, the phase of an acoustic pulse is observed to change upon reflection at the liquid-solid interface if bubbles are present, providing a direct proof for laser-induced bubbles.

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“…It is the repeatable voltammetry facilitated by laser illumination that forms the basis of this electroanalytical technique. We attribute the effect to the cleaning action of the laser pulses which cause thermoelastic stresses [46,52] in the platinum and lead to adsorbed passivating ascorbic acid oxidation products being removed whilst leaving the bulk electrode unscathed. At the same time the diffusion layer is continually refreshed leading to mass transport that is slightly enhanced when compared with voltammetry 'in the dark'.…”

Section: Voltammetry In the Presence Of Laser Activationmentioning

confidence: 99%

“…Instead elastic stresses build up in the metal as a consequence of bulk thermal expansion. This is known as the thermoelastic effect [46,52]. It is only at higher powers that energy absorbed from the laser pulse by the metal is sufficient to give rise to melting or even vaporization of a small amount of surface material.…”

Section: Introductionmentioning

confidence: 99%

“…In early work pulsed lasers were used to depassivate iron surfaces in corrosion studies [44] and prepare silicon surfaces for surface analysis [45]. Subsequently electrochemistry at laser-depassivated iron [46,47] and glassy carbon [48,49] electrodes has been reported. In laser activated voltammetry (LAV) [50] a relatively high power pulsed laser light source is used to produce ablation of an electrode surface.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Comparison Between Pulsed Sonovoltammetry and Low Power Laser Activated Voltammetry for the Electroanalysis of Ascorbic Acid in a Commercial Fruit Drink

Akkermans

Compton

1998

Electroanalysis

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A comparison is made between two 'dual activation' electroanalytical techniques for the detection and measurement of vitamin C (L-ascorbic acid) in a commercially available fruit drink via its two electron oxidation at platinum electrodes. Glucose is found not to interfere with the analytical response. First in sonovoltammetry pulses of 25 Wcm ¹2 are applied and the current response characterized in the 'pulse off' period where a current plateau is attained. Second in laser activated voltammetry a 10 Hz pulsed laser (532 nm, ca. 240 Wcm ¹2 average intensity) is used to 'burn' surface adsorbed passivating species off the electrode. Both methods cause agitation of the solution in the bulk phase or at the electrode-solution interface and lead to regular renewal of the diffusion layer. The mass transport limited oxidation currents so obtained are found to scale with ascorbic acid concentration in media where electroanalysis without simultaneous ultrasonic or laser stimulation may be precluded due to electrode passivation. Application to the quantitative electroanalysis of ascorbic acid in the fruit drinks Ribena and 'No added sugar' Ribena is reported. The results obtained are in excellent agreement with those yielded by independent chemical and electrochemical methods.

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Pulsed Laser Depassivation of Metallic Electrodes in Aqueous Corrosive Media

Cited by 4 publications

References 9 publications

Laser Activated Voltammetry: Mass Transport, Surface Effects and Analytical Applications

Laser Activated Voltammetry: Mass Transport, Surface Effects and Analytical Applications

Bubble nucleation and pressure generation during laser cleaning of surfaces

A Comparison Between Pulsed Sonovoltammetry and Low Power Laser Activated Voltammetry for the Electroanalysis of Ascorbic Acid in a Commercial Fruit Drink

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