offnoob.blogg.se - Bruker apex ylid

Reciprocal space u The immediate result of the X-ray diffraction experiment is a list of X-ray reflections hkl and their intensities I.Diffraction Patterns Two successive CCD detector images with a crystal rotation of one degree per image For each X-ray reflection (black dot), indices h,k,l can be assigned and an intensity I = F 2 measured.The same h, k and l values are used to index the X-ray reflections from the planes. We can index them by the number of times h, k and l that they cut each edge. Reflection Indices These planes must intersect the cell edges rationally, otherwise the diffraction from the different unit cells would interfere destructively.

At other angles, the waves reflected from different planes are out of phase and cancel one another out. Only at certain angles 2 are the waves diffracted from different planes a whole number of wavelengths apart, i.e., in phase.

Braggs law We can think of diffraction as reflection at sets of planes running through the crystal.

X-Ray Diffraction X-ray beam 1 (0.1 nm) ~ (0.2mm) 3 crystal ~10 13 unit cells, each ~ (100) 3 Diffraction pattern on CCD or image plate.

X-Ray Diffraction Pattern from Single Crystal Rotation Photograph.

7 Crystal Systems - Metric Constraints u Triclinic - none u Monoclinic - = 90, 90 u Orthorhombic - = 90 u Tetragonal - = 90, a = b u Cubic - = 90, a = b = c u Trigonal - = 90, = 120, a = b (hexagonal setting) or =, a = b = c (rhombohedral setting) u Hexagonal - = 90, = 120, a = b.

Crystallographic Unit Cell Unit Cell Packing Diagram - YLID.

Select and Mount the Crystal u Use microscope u Size: ~0.4 (0.2) mm u Transparent, faces, looks single u Epoxy, caulk, oil, grease to affix u Glass fiber, nylon loop, capillary.Growing Crystals Kirsten Bttcher and Thomas Pape.Crystal Growing Techniques u Slow evaporation u Slow cooling u Vapor diffusion u Solvent diffusion u Sublimation /ChapterXIV.pdf.Flowchart for Method Adapted from William Clegg Crystal Structure Determination Oxford 1998.Crystal Structure Determination and Refinement Using the Bruker AXS SMART APEX System Charles Campana Bruker Nonius.