due to the oscillating charge in the antenna Along this line one does not observe any acceleration Radiation from a dipole-antenna To get the dimension right ! Electromagnetic radiation Here one observes the full acceleration, but delayed in time by R/c ! Guess that 2

Polarisation P=cos 2 (ψ) P=1

Interference (mathematical) z r k’ Q Number density many wavecrest k 1 2 as drawn #2 is behind #1 for ”in” but ahead for ”out”, therefore ” – ” Phase 0.      1,2 … many

The dream experiment

1,2 … many

 Detector Viewing Field Detector X-ray beam Kr Gas cell Measuring atomic and molecular formfactors from gas scattering

a=[ ]; b=[ ]; c= ; % Ga a=[ ]; b=[ ]; c=2.531; % As

Unit sphere dd dd  r Q r

Fourier transform of a Gaussian

Convolution of 2 Gaussians i.e. h(x) is also Gaussian with

Side View Top View Ring wave (2D) or Spherical wave (3D) Energy density Surface area locally a plane wave

Aperture d Almost plane wave when Perfect plane wave k’ k A point scatterer in the beam Spherical wave Defines the scattering cross section Area is scattering length

 2L L =(N+1)(  2L L =N No real beam is perfectly monochromatic From the 2 equations, derive the longitudinal coherence length P(   wavelength band

No real beam is perfectly collimated P(    D LTLT Here  and B beams in phase A and B out-of-phase show from the figure that With R being the distance from to source observation point A B The transverse coherence length

Absorption

The experimental setup X-rays Sample Rotation Scintillator 20  m CCD  < 2 mdeg E = 8-27 keV 0.7 x 0.7 mm

Tomography Study the bulk structures, 3D Nondestructive Small lengthscales (350 nm) Fra Galathea III Single slice 100 microns

Compton Scattering Energy and momentum conservation