پاورپوینت انیمیشنی ساخت غار های یخی

پاورپوینت انیمیشنی ساخت غار های یخی

اسلاید 1: Rocks Minerals and CrystalsBy Guest ScientistDr. David WalkerLDEO-Columbia University

اسلاید 2: Rocks are made of mineralsThis pallasite meteorite rock came from the edge of the core of an unknown asteroid in our solar system. This thin slab is lit from both the front and back. Magnesium silicate olivine forms amber-colored crystal windows through iron crystals of kamacite and taenite ( the polished metal).

اسلاید 3: Minerals Are CrystallineGeometrical crystal shapes suggest ordered structures.

اسلاید 4: Periodic 3D atomic order = crystals External morphology in regular geometric shapes suggests internal periodic structure, such as for: Layered silicatechloriteRing silicateberyl (gem=emerald)

اسلاید 5: How to Learn the Atomic Order?Put X-ray beams through crystals.X-rays are short electromagnetic waves of wavelength (l) between 0.1 and 10 Angstroms.If waves hit periodic array with spacing d  l then COOPERATIVE SCATTERING occurs ( = DIFFRACTION ).This is NOT the same as taking an X-ray picture in a medical lab and magnifying it.

اسلاید 6: Cooperative ScatteringWaves on Pond with Array of Duck Decoys Ripple train approaches line of ducksl ddd