Application of photothermal spectroscopy to in-situ studies of films on metals and electrodes

Abstract

The technique of photothermal spectroscopy (PTS) with improved Instrumentation was used to study films, such as paints and dyes, on metal substrates. PTS was also used to monitor In situ the formation and spectra of surface layers on electrodes. PTS Investigations of the electrodeposition of Cu and heptylvlologen bromide on a Pt electrode are reported. The technique as described can detect surface layers ~75-100 monolayers. A one-dimensional thermal diffusion model of the PTS effect is also described.

Spectroelectrochemistry

“…In photothermal spectroscopy, a sensitive fast response thermistor is attached to the back of the test electrode with silver epoxy (to achieve a good thermal contact), whilst an identical thermistor is placed in the bulk of the solution [27]. These thermistors are then configured as two branches of a balanced Wheatstone bridge and the electrode is illuminated with a chopped monochromatic light beam.…”

High-sensitivity absorbance determination by laser-induced thermal modulation of electrical conductivity

“…These thermal absorbance techniques offer an important property: an arbitrarily transparent material will give rise to a measurable temperature rise simply by utilization of an arbitrarily powerful light source (if you push hard enough, it will fall over). The most simple thermal absorbance determination relies upon a direct measurement of the temperature rise with a thermocouple (5). Other thermal absorbance techniques utilize indirect measurement of the temperature rise within the sample wherein some property of the sample which undergoes a change with temperature is monitored.…”

Direct Photothermal Measurement of Optical Absorption in a Flow System

“…It was possible to follow oxide or heptyl viologen formation or Cu deposition on Pt/Au electrodes. 18,19 We have had a longstanding interest in open tubular liquid/ ion chromatography, 20 where detection has been 21 and remains the bottleneck. 22 No HPLC technique can be considered complete without sensitive absorbance detection.…”

“…Subsequent work used a second thermistor in the nonilluminated part as a reference. It was possible to follow oxide or heptyl viologen formation or Cu deposition on Pt/Au electrodes. , …”