Da. Berg et al., IN-SITU PHOTOACOUSTIC INVESTIGATION OF THALLIUM UNDERPOTENTIAL DEPOSITION ON POLYCRYSTALLINE COPPER ELECTRODES, Journal of electroanalytical chemistry [1992], 369(1-2), 1994, pp. 33-37
Photoacoustic spectrometry (PAS) was used as an ancillary in-situ tech
nique for the investigation of underpotential deposition (UPD) of thal
lium on polycrystalline copper. The PAS signal generated by 605 nm rad
iation was found to increase upon deposition of Tl on Cu. Since underp
otential deposition is generally a monolayer event, the limit of detec
tion obtained for this technique was estimated to be 0.05 of a monolay
er. The PAS results support the conclusion that the second UPD peak is
due to a second discrete monolayer rather than a filling-in of vacant
sites in the first monolayer. The use of PAS to study the thallium sy
stem at pH 12 confirmed that removal of Cu2O from the electrode surfac
e occurred at a sufficient rate that it did not interfere with the UPD
of thallium.