Secondary-Ion Mass Spectrometry (SIMS)二 次 離 子 質 譜 法

• To determine both the atomic and the molecular composition of soli

d 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)

21D Ion Spectroscopic Techniques

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.

P.605Ch21 Surface Characterization by Spectroscopy and Microscopy

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: C2008 Office Hour: Wed 12:30 – 14:00

Telephone: 3921 E-mail: tshsi@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 %

Mi’croscopy / ‘Microscopeto image the surface

• Optical Microscopy

• Scanning Electron Microscopy (SEM)

• Scanning Tunneling Microscopy (STM)

• Atomic Force Microscopy (AFM)

顯微術 顯微鏡

掃描穿隧顯微術

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:

3-D

atomic scale resolution

地形

?

I-atom

STM

3 nm x 3 nm, on Pt

29

AFM

two double-stranded DNA

mica

30

Scanning Tunneling Microscopy (STM)

HOPC

Microscopy: to image the surface (physical features)

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).

1982- first described by G. Binnig and H. Roher1986- Nobel Prize in Physics

地形圖

24

e.g.,

V : !.5 V

d : 2 nm

It : 100 pA

It = V e-kd

tunneling current

Probe : single atom tip (W, Pt)

C - atom

Distance (nm)

const

(exponential decay with d)tunneling current

constant

It = V e-kd

distance

pi’ezoelectric scanner

Stepping-motor

步進馬達

壓電

nm range

μm range

26

Schematic view of an STM