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Group 2Group member:
9931836 陳耀祥9731531 楊智傑9931681 沈盛慶9931600 林哲億
• 1.Introduction -Basic concept & scan modes
• 2.Instrument -Cell design & fabrication of tips
• 3.Application -Biological and Electrochemical researches
• 4.Conclusion & References
Outline
1.Introduction –basic conceptConstruction:
Position control
i-V control
In chemical solution system
Ultramicroelectrode
During the chemical reaction occurred at tip, a small current will be measured ! Signal: Current
Affect factor :1.Topography ---- Morphology2.Reaction type --- Reaction step3.Reaction rate --- Reaction constant
1.Introduction –Scan modes– Feedback modeApproach curve
Far from substrate
Close to substrate
Tunnealing current
Full hindered
RneO
R oxidize to O
1.Introduction –Scan modes– Feedback mode
Practical sample for conductive substrate
BCD
E
Approach curve for conductive substrate
1.Introduction –Scan modes– Collection-Generate modes
1. TG/SC mode
1. SG/TC mode
BneA
Set tip and substrate in different potentials, compare the current difference between tip and substrate
Reaction constant !
Set tip and substrate in different potentials, scan the surface to measure the current
Hot spot !
An illustration of the SECM instrument.
2.Instrument
2.Instrument –Cell design
Size limitation control by dithiol concentration or by the size of pulled capillary.
Diameter greater than 15–20 μm were very fragile and had a tendency to split open.
2.Instrument –Fabrication of tips
carbonization Immersion indithiol
Charge-transfer at the liquid/liquid interface3.Application –Electrochemical researches
Ion-transfer at the liquid/liquid interface
3.Application –Electrochemical researches
1
23
4
5
6
A3+ + B → A2+ + B+
A2+ +e- → A3+
3.Application –Electrochemical researchesLateral mass transfer
A3+ → A2++e-
Lateral charge transfer
determination of DCT
3.Application –Electrochemical researches
OsIIfilm + Ru(CN)6
3-aq ↔ OsIII
film + Ru(CN)64-
aq
IMAGING MOLECULAR TRANSPORT ACROSS MEMBRANES
I. Tip Collection
II. Negative Feedback
II. Combined Mode
[]=100mM
[]=10mM
[]=100mM
[]=0mM
[]=10mM
[]=1mM
3.Application –Biological researches
Generation/Collection Mode
Feedback Mode
3.Application –Biological researches
Constant Impedance Mode
LOCALLY CONTROL REACTION3.Application –Biological researches
4.Conclusion
1.SECM is suitable for observation of surface reaction in liquid system
2.Not only morphology, but also other properties can be measured by different modes in SECM
3.SECM can be applicated in microfabrication and biological sensoring.
Thanks for your attention!
4.References
1. Bard, A. J., & Mirkin, M. V. (2001). Scanning electrochemical microscopy. New York: Marcel Dekker
2. Phys. Chem. Chem. Phys., 2007, 9, 802–8233. Anal. Chem. 1998, 70, 1307 – 13114. J. Phys. Chem. 1995, 99, 16033-160425. J. Electroanal. Chem. 439 1997 137–1436. J. Phys. Chem. B 2001, 105, 11120-111307. J. Phys. Chem. B 2004, 108, 7219-7227
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