双发光体同步发射的光谱电化学发光研究

As can be observed in Figure 2, the linear sweep voltammogram (blue line) shows an oxidation peak at 0.30 V, corresponding to the electrochemical oxidation of luminol in the presence of hydrogen peroxide. It also generates the emission of light at 425 nm, which is recorded by the photodiode as total light emission (green line). The ECL and electrochemical peaks match exactly at 0.30 V.

The ECL signal of luminol in the presence of hydrogen peroxide shows its characteristic behavior with the emission intensity increasing during the oxidation of luminol [3,4]. 

Repeating the experiment with the microspectrometer as detector shows the same electrochemical response (blue line Figure 2), but the optical response is different as the microspectrometer differentiates between wavelengths. The recorded spectrum displays a single emission band at 425 nm, as seen in Figure 3a. 

The evolution of the emission at 425 nm as a function of the potential can be obtained using the «Spectra vs EC» tool in DropView SPELEC. As can be seen in Figure 3b, the ECL behavior matches exactly with the ECL response obtained by the photodiode detector (green line Figure 2). The ECL emission reaches a maximum when the oxidation peak of luminol at 0.30 V is electrochemically observed.

Analysis of this system using the ECLPHOTODIODCELL provides the electrochemical (blue line) and ECL (green line) responses shown in Figure 4. As only luminol undergoes electrochemical oxidation, the voltammogram is identical to the one without fluorescein (Figure 2). The photodiode detector records an increase in total ECL intensity during the oxidation of luminol at 0.30 V. However, as photodiode does not record the emission spectra it cannot distinguish the luminol and fluorescein contributions.

When the experiment is repeated using the microspectrometer cell, the electrochemical behavior remains the same (blue line Figure 4), but the ECL displays two emission bands. Figure 5a shows the spectra recorded during the linear sweep voltammetry. The band at 425 nm corresponds to the luminol emission while the band at 530 nm is associated with the emission of fluorescein. This confirms RET from luminol to fluorescein and demonstrates the ability of the microspectrometer to differentiate between emissions from different luminophores.

The potential-dependent evolution of the emissions is analyzed using the «Spectra vs EC» tool in DropView SPELEC. As can be observed in Figure 5b, the emissions of both luminol and fluorescein increase during the oxidation of luminol and reach their maxima at 0.30 V. The spectro-electrochemiluminescence response also allows the evaluation of each luminophore’s contribution, showing that the luminol emission is higher than the fluorescein signal.