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 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 radiation The spectrum of the electromagnetic radiation of interest in surface science

Interaction of surface/interface science with physics and engineering Condensed matter physics

Countries where surface physics is performed (source 1993, : Briggs, Seah, see References) - Journals - 1 billion USD invested in set-ups

Relation between surface physics and various industries (UK, 1997) (source 1993, : Briggs, Seah, see References)

Surface techniques and information that they provide

Research 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 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) 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) 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, [2] C. Desjonqueres, D. Spanjaard, Concepte de fizica suprafetei, Ed. Tehnică (Romanian) [3] H. Lueth, Surfaces and interfaces of solid materials, Springer, [4] P. Atkins, J. de Paula, Physical Chemistry, Ed. 8, Oxford, [5] D. Briggs, M. P. Seah, Practical surface analysis, vol I, II, Willey and Sons, Ed. II References