X-Ray Diffraction System

X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) both identify a material's internal structure without destroying the sample — XRD reveals crystal structure and strain by how a material diffracts X-rays, and FTIR reveals chemical bonding and composition by which infrared frequencies a material absorbs.

XRD's diffraction pattern is a direct geometric signature of atomic spacing, which is why it can distinguish crystal phases that look identical by any chemical-composition measurement alone. Two materials with the exact same elemental composition can still differ in crystal structure — different polytypes of silicon carbide are a direct example, and the diagnosis matters enormously since the wrong polytype has different electronic properties entirely. XRD measures how X-rays diffract off the material's periodic atomic lattice, producing a pattern that depends purely on atomic spacing and symmetry — information no elemental-composition technique like EDS or EPMA can provide, since those only answer "what atoms are present," not "how are they arranged."

FTIR's absorption peaks act as a direct fingerprint of specific molecular bonds, which makes it especially useful for identifying organic contamination and residue that neither XRD nor elemental techniques characterize well. Each type of chemical bond — a particular carbon-hydrogen stretch, a specific carbonyl group — absorbs infrared light at characteristic, well-cataloged frequencies, so an FTIR spectrum of an unknown residue or film can often be matched directly against known reference spectra to identify exactly what organic compound is present; this makes FTIR a go-to technique for identifying unknown organic contamination that elemental or crystal-structure methods simply aren't designed to characterize.

XRD and FTIR together cover two kinds of structural information neither elemental composition techniques nor imaging tools provide on their own — how a material's atoms are arranged into a crystal lattice, and what specific chemical bonds hold a material or contaminant together — both read non-destructively straight from how the sample interacts with X-rays or infrared light.