TY - JOUR

T1 - Scanning electrochemical microscopy. 41. Theory and characterization of ring electrodes

AU - Lee, Y.

AU - Amemiya, S.

AU - Bard, A. J.

PY - 2001/5/15

Y1 - 2001/5/15

N2 - Ring ultramicroelectrodes, which are of particular interest as probes for scanning electrochemical microscopy (SECM), combined with near-field scanning optical microscopy, were investigated. Theoretical SECM tip current-distance (approach) curves for a ring electrode were calculated by numerical (finite element) analysis. The SECM curves obtained were a function of the geometry of the tips including the thickness of the ring and the insulating sheath. Theoretical approach curves over conductive substrates showed a strong dependence on the ratio of inner to outer radii of ring microelectrodes (a/b) and were relatively insensitive to the thickness of the insulating sheath (rg). For insulating substrates, however, the approach curves varied significantly with rg, but much less with the a/b ratio. Comparison of experimental and theoretical SECM curves provided a good method of evaluating the size and shape of ring electrodes. Good agreement of the experimental and theoretical curves was found with a ring microelectrode with a nominal 200-nm ring thickness, yielding values of 1.7, 1.9, and 5.7 μm for the inner (a) and outer (b) radii of a ring and the outermost radius of insulating sheath (rg), respectively.

AB - Ring ultramicroelectrodes, which are of particular interest as probes for scanning electrochemical microscopy (SECM), combined with near-field scanning optical microscopy, were investigated. Theoretical SECM tip current-distance (approach) curves for a ring electrode were calculated by numerical (finite element) analysis. The SECM curves obtained were a function of the geometry of the tips including the thickness of the ring and the insulating sheath. Theoretical approach curves over conductive substrates showed a strong dependence on the ratio of inner to outer radii of ring microelectrodes (a/b) and were relatively insensitive to the thickness of the insulating sheath (rg). For insulating substrates, however, the approach curves varied significantly with rg, but much less with the a/b ratio. Comparison of experimental and theoretical SECM curves provided a good method of evaluating the size and shape of ring electrodes. Good agreement of the experimental and theoretical curves was found with a ring microelectrode with a nominal 200-nm ring thickness, yielding values of 1.7, 1.9, and 5.7 μm for the inner (a) and outer (b) radii of a ring and the outermost radius of insulating sheath (rg), respectively.

UR - http://www.scopus.com/inward/record.url?scp=0035872326&partnerID=8YFLogxK

U2 - 10.1021/ac0014764

DO - 10.1021/ac0014764

M3 - Article

C2 - 11393850

AN - SCOPUS:0035872326

SN - 0003-2700

VL - 73

SP - 2261

EP - 2267

JO - Analytical Chemistry

JF - Analytical Chemistry

IS - 10

ER -