Plan : intro

Characterization of thin films and bulk materials using x-ray and electron scattering

V. Pierron-BohnesIPCMS-GEMME, BP 43, 23 rue du Loess, 67034 Strasbourg Cedex 2

electronic properties magnetism, optics, transport…

structural properties

preparation conditionssmall dimensions

Research topics:- superalloys NiAl, FeAl, (Co,Fe,Mn)Pt3 (order – kinetics – magnetism)- multilayers Co/Mn, Co/Ru (stucture – magnetism)- anisotropic alloy thin films (MBE, sputtering) CoRu, CoPt, FePt, NiPt

-(structure – magnetism – interdiffusion)

Plan : interactions

Characterization of thin films and bulk materials using x-ray and electron scattering

V. Pierron-BohnesIPCMS-GEMME, BP 43, 23 rue du Loess, 67034 Strasbourg Cedex 2

1) electron and x-ray interaction with matter2) real lattice and reciprocal lattice in 3D and 2D samples3) experimental set-ups4) studies on single crystals 5) synchrotron radiation 6) strains measurements using x-ray scattering and TEM7) powder scattering measurement8) texture analysis9) reflectometry10) chemical analysis11) short and long range order measurements

electron-matter interaction 1An electron has:- a mass:9.1 x 10-31 kg - a charge1.6 x 10-19 Cto interact with other electrons and nuclei

in V511 kV

Vacc=100kV =0.0037 nm

electron-matter interaction 2

Electronic structure of atoms

electron-matter

interaction 3

energy loss electron

Incident electron

secondary electron (E < 50eV)

Transmitted beam with energy loss

electron-matter

interaction 4

primary electron

energy loss electron

incident electron

Emission of a primary electronInelastically scattered electron

electron-matter

interaction 5

Auger electron

energy loss electron

photon

wavelength

inte

nsi

ty

dis-excitation

electron-matter

interaction 6

secondary electron (E < 50eV)

Emission of a secondary electron

x-ray interaction with

matter

Incident x-ray beam

E = h0Rayleigh + Thomson

diffusion (coherent + elastic)

E ≈ h0

Compton diffusion (incoherent

+ slightly inelastic)

E ≠ h0

Absorption + reemission: fluorescence… (incoherent

+ strongly inelastic)

E = h0

X-rays: no mass, no charge → interaction as the effect of electro-magnetic field on charges

electrons(photoelectric

effect)

Thomsonsmall

large h0

x-ray-matter

interaction

Incident x-ray beam

E = h0Rayleigh + Thomson

diffusion (coherent + elastic)

E = h0

Rayleighlarge

small h0

x-ray-matter

interaction

Incident x-ray beam

E = h0 E ≈ h0

Compton diffusion (incoherent

+ slightly inelastic)

nucleus

hole

Photon: particle with E = h and p = hc/

=

with

x-ray-matter

interaction

Incident x-ray beam

E = h0Compton diffusion

(incoherent+ slightly inelastic)

E << h0

Absorption + reemission: fluorescence… (incoherent

+ strongly inelastic)

excited electron

incident photon

emittedphoton

Incident x-ray beam

E = h0

photoelectric effect

e-

nucleus

hole

Energy

probabilty

x-ray-matter

interaction

x-ray interaction with matter

Incident x-ray beam

E = h0Rayleigh + Thomson

diffusion (coherent + elastic)

E ≈ h0

Compton diffusion (incoherent

+ slightly inelastic)

E ≠ h0

Absorption + reemission: fluorescence… (incoherent

+ strongly inelastic)

E = h0

electrons(photoelectric

effect)

Hard x-rays : within 0.01 – 0.1nm

Soft x-rays: within 0.1 – 0.25 nm

x-ray diffusion by one electron

electron acceleration

field emitted in direction k

=/2

angle between k and

E

E

2

per solid angle

x-ray diffusion by one atom

Electronic distribution electronic

states

atomic volume

Contribution of extended states

Contribution of localized states

Interference effects(diffusion factor)

Hartree-Fock calculations:

F

dependent on the energy only

dependent on the direction only

diffusion factor at absorption edge

absorption edge

energy

anomal diffraction:enhanced contrastat the edge of the

light element

Mn edge

Cromer –Liberman method

Relations between , f’ and f’’Kramers-Kronig relations

f’ and f” obey the Kramers-

Kronig relations

Absorption: the intensity decreases as exp(-z)

Maxwell equations If is complex, k is complex

because

or : in the international tables of crystallography

x-rays pass through some m atomic volume

Sasaki tables

Co edge

electron diffusion by one atom

The deviation of the electron is due to their electrostatic interactionbecause the mechanical interaction (collision) has a too small probability

The elastic part is due to the deviation by the electric potential due to both nuclei and electrons, but the nuclei is predominant.

≈ Q-2

compared diffusion amplitudes

compare scattering amplitudes and

atomic scattering

factors for x-rays, electrons and neutrons

comparison of the thickness to absorb99% of the beamfor different rays

absorption