Atomic structure Molecular structure 31 Atomic/Molecular Structure and Spectra 29 Spectrum analysis 29 Physics 18 Chemistry, Physical and theoretical 10 Physical Chemistry 9 Quantum theory 9 Chemistry 8 Microscopy 6 Quantum Physics 6 Spectroscopy and Microscopy 6 Solid state physics 5 Spectroscopy/Spectrometry 5 Molecular Medicine 4 Molecular biology 4 Biochemistry 3 Biomedicine 3 Condensed matter 3 Human Physiology 3 Human physiology 3 Mathematical Methods in Physics 3 Medicine 3 Solid State Physics 3 Theoretical and Computational Chemistry 3 Animal Biochemistry 2 Atoms 2 Biological and Medical Physics, Biophysics 2 Cell Physiology 2 Cell physiology 2