Transcript 二 次 離 子 質 譜 法

21D Ion Spectroscopic Techniques
Secondary-Ion Mass Spectrometry (SIMS)
二次離子質譜法
•
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)
21E Surface Photon Spectroscopic Methods
Disadvantages of XPS, AES and SIMS:
• require ultra-high vacuum
• can not deal with surfaces in contact with liquid
Surface Plasmon Resonance, SPR 表面電漿共振
• 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.
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.
Ch21 Surface Characterization by Spectroscopy and Microscopy
P.605
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.)
Course:
Instrumental Analysis
Spring 2007
Instructor: Dr. Tai-Sung Hsi (眭台生)
Office:
Office Hour: Wed 12:30 – 14:00
C2008
Telephone: 3921
E-mail: [email protected]
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 %
顯微術
顯微鏡
Mi’croscopy / ‘Microscope
to image the surface
•
Optical Microscopy
•
Scanning Electron Microscopy (SEM)
•
Scanning Tunneling Microscopy (STM)
•
掃描穿隧顯微術
Atomic Force Microscopy (AFM)
原子力顯微術
STM / AFM = Scanning Probe Microscope (SPM)
• x/y raster pattern: a scanning pattern
• To measure the surface to’pography of sample:
地形
3-D
atomic scale resolution
STM
29
I-atom
3 nm x 3 nm, on Pt
?
AFM
two double-stranded DNA
mica
30
Scanning Tunneling Microscopy (STM)
Microscopy: to image the surface
(physical features)
C - atom
1982- first described by G. Binnig and H. Roher
1986- Nobel Prize in Physics
• 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).
24
HOPC
地形圖
Probe : single atom tip (W, Pt)
tunneling current
Distance (nm)
It = V e-kd
const
e.g.,
C - atom
V : !.5 V
d : 2 nm
It : 100 pA
tunneling current (exponential decay with d)
It = V e-kd
constant
distance
pi’ezoelectric scanner
壓電
nm range
Stepping-motor
步進馬達
μm range
26
Schematic view of an STM