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