Secondary-Ion Mass Spectrometry (SIMS) ? ? ? ? ? ? ?

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Secondary-Ion Mass Spectrometry (SIMS)? ? ? ? ?
? ?
21D Ion Spectroscopic Techniques

• To determine both the atomic and the molecular
  composition of solid surface.
• Primary beam ions (e.g., Ar)
• bombard the surface
  of the sample
• Secondary beam ions (both atoms and molecules)
• to be
  determined by a mass analyzer (e.g.,
• quadrupole,
  time-of-flight)

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21E Surface Photon Spectroscopic Methods

• Disadvantages of XPS, AES and SIMS
• require ultra-high vacuum
• can not deal with surfaces in contact with liquid

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Surface Plasmon Resonance, SPR ??????

• surface plasmon waves the surface
  electromagnetic waves that propagate
• in the
  xy plans of a metal film when the free
• 
  electrons interact with photons.
• total internal reflection
• With total internal reflection, an evanescent
  wave is generated in the
• medium of lower refractive index.
• When the angle is suitable for surface plasmon
  resonance, a sharp
• decrease in the reflected intensity is observe.
• The most interesting aspect of surface plasmon
  resonance (SPR) is its
• sensitivity to materials adsorbed onto the
  metal film.
• SPR has become an important technique for
  biosensors.

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• FIGURE 21-14 Surface plasmon resonance. Laser
  radiation is coupled into
• the glass substrate coated with a thin metal film
  by a half-cylindrical prism. If
• total internal reflection occurs, an evanescent
  wave is generated in the
• medium of lower refractive index. This wave can
  excite surface plasmon
• waves. When the angle is suitable for surface
  plasmon resonance, a sharp
• decrease in the reflected intensity is observed
  at the detector.

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Homework 1 What is self-assembled monolayer
(SAM)? 1 2 pages (A4) Good figures/tables are
often useful. List the references in correct
format. Be sure to include at least one reference
book. Due 03/06 (Thur.)
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Course Instrumental Analysis

Spring 2007 Instructor Dr. Tai-Sung Hsi
(???) Office C2008

Office Hour Wed 1230 1400 Telephone 3921

E-mail tshsi_at_mail.nsysu.edu.tw
Textbook D.A. Skoog, F.J. Holler and T.A.
Nieman, Principles of Instrumental Analysis,
5th ed., Harcourt Brace
Company, Philadelphia, 1998. References 1. D.
C. Harris, Quantitative Chemical Analysis, 6th
ed., W. H. Freeman and
Company, New York, 2003.
2. J. W. Robinson, E. M. S. Frame and G. M. Frame
II, Undergraduate Instrumental
Analysis, 6th ed., Marcel Dekker, New
York, 2005. 3. G. D.
Christian and J. E. O'Reilly, Instrumental
Analysis, 2nd ed., Allyn and
Bacon, Boston, 1986.
4. R. D. Braun, Introduction to Instrumental
Analysis, McGraw-Hill, New York,
1987. Grade Homework Quiz 15
Examination x 3 89
(100 105 110) / 3 x 85
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Microscopy / Microscopeto image the surface
??? ???

• Optical Microscopy
• Scanning Electron Microscopy (SEM)
• Scanning Tunneling Microscopy (STM)
• Atomic Force Microscopy (AFM)

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STM / AFM Scanning Probe Microscope (SPM)

• x/y raster pattern a scanning pattern
• To measure the surface topography of sample
• 3-D
• atomic scale resolution

??
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STM
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I-atom
3 nm x 3 nm, on Pt
?
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AFM two double-stranded DNA
mica
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Scanning Tunneling Microscopy (STM)
Microscopy to image the surface
(physical features)
1982- first described by G. Binnig and H.
Roher 1986- Nobel Prize in Physics
C - atom

• Tunneling current Two conductors are
• within a few nanometers of one another,
• and one of the conductor is in the form
• of a sharp tip.
• The tunneling current is held constant to
• remain d constant.
• The surface being examined must
• conduct electricity (i.e., a conductor or
• semiconductor).

HOPC
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???
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Probe single atom tip (W, Pt)
Distance (nm)
tunneling current
It V e-kd
const
e.g., V !.5 V d 2 nm It 100 pA
C - atom
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(exponential decay with d)
tunneling current
It V e-kd
constant
distance
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piezoelectric scanner
??
nm range
Stepping-motor ????
µm range
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Schematic view of an STM