Scanning Electrochemical Microscopy-Electrogenerated Chemiluminescence

1 Using the SECM Tip as a Light Source for Scanning Optical Microscopy 

One motivation for coupling SECM with ECL is to be able to use the SECM tip as a controllable light source that locally illuminates the sample surface. To achieve this, the tip is biased so as to trigger an electrochemical reaction that produces light by chemiluminescence. The sample surface has to be at least partly transparent and the emitted light is collected by a PMT tube located below the substrate. The ECL intensity measured by the PMT can then be plotted as a function of the tip position to form an image that reflects the local optical properties of the substrate, for example, its absorbance. The setup is similar to the one used for SECM-OM described earlier in Section 17.5.2. 

When the tip was approached toward an insulator, the ECL intensity was observed to be steady until the tip was within a few tenths of the tip radius away. A sharp drop of the ECL intensity was recorded upon closer approach due to hindered diffusion of the ruthenium species in the tip-substrate gap. When the tip was approached toward a conducting substrate, the ECL intensity was 

Einally, it is worth noting that SECM-ECL has been used to investigate the mechanism of ECL emission for the Ru(bpy)3 -TrPA and Ru(bpy)3 -oxalate systems [141,143]. 

---

Lei, R., Stratmann, L., Schafer, D., Erichsen, T., Neugebauer, S., Li, N., Schuhmann, W., Imaging bio-catalytic activity of enzyme-polymer spots by means of combined scanning electrochemical microscopy/ electrogenerated chemiluminescence. A aZ. Chem. 2009, 81, 5070-5074. 

Lei R, Stratmann L, Schafer D, Erichsen T, Neugebauer S, Li N, Schuhmann W (2009) Imaging biocatalytic activity of enzyme-polymer spots by means of combined scanning electrochemical microscopy/electrogenerated chemiluminescence. Anal Chem 81 5070-5074... 

Fan F-RF, Cliffel D, Bard AJ (1998) Scanning Electrochemical Microscopy. 37. Light emission by electrogenerated chemiluminescence at SECM tips and their tq>plication to scanning optical microscopy. Anal Chem 70(14) 2941-2948. doi 10.1021/ac980107t... 

Kanoufi, R, C. Cannes, Y. B. Zu, and A. J. Bard, Scanning electrochemical microscopy. 43. Investigation of oxalate oxidation and electrogenerated chemiluminescence across the liquid-liquid interface, J Phys Chem B, Vol. 105, (2001) p. 8951. 

---