Infrared reflection–absorption spectroscopy applied to a merocyanine dye J-aggregate deposited on transparent electrodes based on zinc oxide

Formation of ionic bonds between a fatty-acid Langmuir–Blodgett monolayer and a zinc oxide substrate

“…This is proven by the fact that the x(CH 2 ) modes are clearly seen for the 3-layer C 20 sample. (Detection of those modes was difficult for the stacked monolayers of an alkylated merocyanine dye on ZnO substrates [8], but in that case the gauche conformation in the alkyl chains may largely weaken the modes' amplitudes.) The possible combination with the conventional UV absorption technique [8] is an advantage of the ZnO substrate when compared with the conventional IR-RAS substrates such as Au [9][10][11][12].…”

“…The properties of the GZO and AZO films, which were used after sonication in chloroform and acetone, were the same as those of the samples used in previous works [7,8]. C 20 and deuterated C 20 (C 20 -d 39 ) were purchased from Fluka AG and CDN Isotopes Inc., respectively, and dissolved in chloroform (1 Â 10 À3 mol/L).…”

“…It should be noted that in the indium-tin-oxide (ITO) case, oxygen-plasma etching and heat treatment were necessary as such processes before and after immersing the substrate in solutions of phosphonic acid modifiers [6]. Second, owing to its plasma frequency being much higher than the molecular vibration frequencies and large reflectance in the infrared (IR) region [7], IR reflection-absorption spectroscopy (RAS) can be performed with the ZnO-based conductor [8]. This method utilizes the electric-field enhancement due to condensed free electrons in the substrate and therefore is quite sensitive.…”

Infrared Reflection-Absorption Spectra of Calcium Icosanate Langmuir-Blodgett Films Observed by Using Zinc Oxide-Based Transparent Electrode and Gold

“…Moreover, some vibronic absorption bands assignable to the carboxylic group are clearly seen even for the 1-layer sample (Fig. 3 (a) The ν s (COO -) and COH deformation modes are overlapped with each other.. the aggregating state of a merocyanine dye in a monolayer-like system deposited on Ga-doped ZnO substrates could be investigated by the IR-RAS method [6]. Quantitative comparison with the IR-RAS on the Au substrates should be done for thicker samples.…”

“…More recently, we demonstrated that the simple IR-RAS method is effective in characterizing organic materials deposited on a transparent electrode based on Ga-doped zinc oxide covered with a buffer layer, even when the quantity of the material is at the monolayer level [6]. Namely, the correlation between formation of the J-aggregate and changes in electronic structure of the dye chromophore was clearly shown by comparing the usual transmission visible spectra and IR-RAS signals of a merocyanine-dye LB films deposited with and without a divalent metal cation.…”