Laser pulses of short duration (10 ns) and high intensity (20 MW cm/sup -2/) can increase the rate of heterogeneous electron transfer at a glassy carbon electrode by 1-3 orders of magnitude. The laser pulse may be delivered in situ, directly in the solution of interest, repeatedly if desired. The heterogeneous electron transfer rate constant, k/sup 0/, for the ferri-/ferrocyanide redox system increases from 0.004 to 0.20 cm s/sup -1/ with laser activation, resulting in the highest k/sup 0/ yet observed for this system on glassy carbon. Laser activation results in minor morphological changes to the surface, as observed by scanning electron microscopy, mainly removal of an apparent layer of carbon microparticles. The technique holds promise as a means to repeatedly activate glassy carbon electrodes in situ, thus circumventing the need for renewal or reactivation by polishing or other ex situ treatments.

In situ laser activation of glassy carbon electrodes

Vieillisement rapide en quelques heures, mais ensuite bonne stabilite au moins sur 24 heures

Amperometric response of microlithographically fabricated microelectrode array flow sensors in a thin-layer channel

In situ cleaning and activation of solid electrode surfaces by pulsed laser light

Polycrystalline spinel ferrite films were plated on glass substrates in an aqueous solution by the thin liquid‐film method combined with an electric lamp, which was named ‘‘light‐enhanced ferrite plating.’’ By irradiating the substrate surface with a Xe lamp (450 W/cm2), the deposition rate of Fe3O4 films increased by a factor of ∼5–10 (from 30 to 150–320 nm/min) compared to that obtained without the light irradiation. The Fe3O4 film prepared in a reaction solution with a small FeCl2 concentration had a structure (i.e., grain size ∼200 nm, and columnar structure perpendicular to the film surface) similar to that observed when prepared without the light irradiation. However, the grain size increased and the columnar structure disappeared as the FeCl2 concentration increased. The deposition rate of Fe3−xMxO4 (M=Ni, Mn, Co, and Zn) was 50–100 nm/min and increased by a factor of 2–5 compared to that without the light irradiation. The saturation magnetization of the all films prepared with the light irradiatio...

Light‐enhanced ferrite plating of Fe3−xMxO4 (M=Ni, Zn, Co, and Mn) films in an aqueous solution (invited)

Laser-enhanced processes have found an increasingly important role as the interest in microfabrication continues to grow. An especially attractive feature of laser processing in liquids is the ability to obtain maskless patterning in the form of material deposition or dissolution, dictated by the path of the focused laser on the sample. In the present discussion we review theoretical and experimental aspects of laser-enhanced plating and etching for a variety of materials. Some of the substrates readily etched with the help of the laser are extremely difficult to process by conventional methods. Even though the laser processes can handle materials only in a serial manner, the plating and etching rates in certain instances are sufficiently rapid to make them competitive with batch processing methods. This is particularly interesting as it pertains to laser-enhanced jet plating of copper and gold, where rates as high as 50 and 20 µm/s have respectively been obtained.

Electrochemical microfabrication by laser-enhanced photothermal processes

Laser-enhanced electroplating on good heat-conducting bulk materials is not very effective, as laser-beam irradiation results in a limited temperature rise only. It is shown, both experimentally and theoretically, that the application of a thin layer of a relatively poor heat-conducting material may lead to a considerable local temperature increase. The dimensionless parameter determining this effect is given by the product of the ratio of the thermal conductivities of bulk and layer material and that of layer thickness to laser-spot diameter.

H. K. Kuiken

Papers

Laser‐Enhanced Electroplating on Good Heat‐Conducting Bulk Materials