Which technique gives better atomic resolution than NMR?
X-ray crystallography achieves true atomic resolution, routinely 1.0 to 2.5 angstroms, far surpassing typical NMR ensembles. Crystals contain billions of molecules in ordered lattices; X-rays scattered by electrons interfere constructively following Bragg's law, producing diffraction patterns that encode structure factor amplitudes. After solving the phase problem via molecular replacement or heavy-atom methods, inverse Fourier synthesis generates electron density maps revealing individual atoms, side-chain rotamers and bound ligands. Circular dichroism only estimates average secondary structure, infrared identifies functional groups, and mass spectrometry measures mass, lacking three-dimensional coordinate information.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.