Methods and Tehniques in Surface Science

Prof. Dumitru LUCA

“Alexandru Ion Cuza” University, Iasi, Romania

Introduction. Relation between surface/interface science and other fields of knowledge

1. What is the surface?

2. How can the surface be probed?

3. What kind of probing particles should be used?

4. What kind of emergent particles can be detected?

- electrons, ions, low-energy neutrals:

1-10 ML

- Scattered, absorbed, emitted particles – the essential source of information.

Photon excitationPhoton excitation

HIGH penetration depth,

but…

LOW probing depth when using non-photon emerging particles:

Photon sources:

• Incandescent lamp

• Glow discharge lamp

• Lasers

• X-ray sources

• Sincrotron radiationThe spectrum of the electromagnetic radiation of interest

in surface science

Interaction of surface/interface science with Interaction of surface/interface science with physics and engineeringphysics and engineering

Condensed matter physics

Countries where surface physics is performed (source 1993, : Briggs, Seah, see References)

- Journals

- 1 billion USD invested in1997

- 2500 set-ups

Relation between surface physics and various Relation between surface physics and various industries (UK, 1997)industries (UK, 1997)

(source 1993, : Briggs, Seah, see References)

Surface techniques and information that they provideSurface techniques and information that they provide

Research strategies in surface scienceResearch strategies in surface science

What is expected from surface physics?

Making clear the mechanisms (at molecular/atomic levele) involved in a certain behavior of the surface….

….HOWEVER….

The surface theory is by far much simpler to develop for idealized surfaces (single crystals, clean surfaces or surfaces covered by adsorbants, in a controllable manner)

Nowadays, we are able to develop theoretical models for “tehnical” surfaces at a satisfacory level.

…BUT…

-The verifying the results predicted by the models is frequently not necessarily straightforward:

most of the surface techniques require using the UHV, while the real applications work at atmospheric pressure, and sometimes at high temperatures.

Research strategies in Surface Physics

A complementary approach - measurements:

(a) in real time in situ (XRD, Moessbauer, infrared, EXAFS)

(b) after “quenching” the investigated state.

Real conditions

(p =1 atm, high-temp.)Real

materials/surfaces

UHV Single cristal

Completing the above-mentioned information via:(i) modelling on single-crystals(ii) using UHV techniques

Usual techniques in Surface ScienceUsual techniques in Surface Science

1. Temperature programmed techniques (TPD)

1a. Temperature programmed reduction (TPR)

1b. Temperature programmed sulphidation (TPS) – catalysis

1c. Temperature programmed reaction spectroscopy (TPRS).

2. Photoemission spectroscopies

2a. X-ray Photoelectron spectroscopy (XPS)

2b. Ultraviolet photoelectron spectroscopy (UPS)

- Auger Emission spectroscopy

3. Ion spectroscopies

3a. Low-energy ion scattering (LEIS)

3b. Secondary ion mass spectrometry (SIMS)

3c. Secondary neutral mass spectrometry (SNMS)

3d. Rutherford backscattering (RBS)

Usual techniques in Surface Science (cont’d)Usual techniques in Surface Science (cont’d)

4. Moessbauer spectroscopies

4a. Moessbauer Absorption Spectroscopy (MAS)

4b. Moessbauer Emission Spectroscopy (MES)

5. Diffraction methods [X-Ray Diffraction (XRD), Low-Energy Electron Diffraction (LEED)

and EXAFS (Extended X-ray Absorption Fine Structure).

6. Microscopy and si imagistics

6a. Transmission Electron Microscopy (TEM)

6b. Scanning Electron Microscopy (SEM)

6c. Electron Microprobe Analysis (EMA)

6d. Energy Dispersive X-ray Analysis (EDX/EDAX)

6e. Field Emission Microscopy (FEM)

Usual techniques in Surface Science (cont’d)Usual techniques in Surface Science (cont’d)

6f. Field Ion Microscopy (FIM)

6g. Atomic Force Microscopy (AFM)

6h. Scanning Tunneling Microscopy (STM)

6i. Photoemission Electron Microscopy (PEEM)

6j. Ellipsometry Microscopy for Surface Imaging (EMSI)

7. Vibration spectroscopies

7a. Infrared Spectroscopy (IS)

7b. Transmission Infrared Spectroscopy (TIS)

7c. Diffuse reflectance Infrared Spectroscopy (DRIS)

7d. Raman Spectroscopy

7e. Electron Energy Loss Spectroscopy (EELS)

8. Wettability, contact angle, Surface free energy

8a. Sessile drop: static/dinamic measurements (advancing, receding

angle)

8b. Hidrophobicity-hidrophilicity

[1] H. P. Myers, Introductory Solid State Physics, Taylor&Francis, 1990 .

[2] C. Desjonqueres, D. Spanjaard, Concepte de fizica suprafetei, Ed. Tehnică. 1998 (Romanian)

[3] H. Lueth, Surfaces and interfaces of solid materials, Springer, 1993.

[4] P. Atkins, J. de Paula, Physical Chemistry, Ed. 8, Oxford, 2006.

[5] D. Briggs, M. P. Seah, Practical surface analysis, vol I, II, Willey and Sons, Ed. II 1990.

ReferencesReferences