Gerhard Herzberg won the 1971 Nobel Prize in Chemistry "for his contributions to the knowledge of electronic structure and geometry of molecules, particularly free radicals" Gerhard Herzberg is a physicist who has made many contributions to the fields of atomic and molecular spectroscopy. Spectroscopy is the study mater with radiated energy (such as electromagnetic waves). An atom’s energy levels are discreet or quantized as described in quantum mechanics, so only certain discreet energies, or frequencies, are observed and these act as characteristic signatures. For atoms they provide information about the electron structure. For molecular spectroscopy, the energies observed gives insight into bond energies, electronic structure, and the geometry of the molecule. Herzberg also utilized this information to identify molecules in comets, interstellar space, and planetary atmospheres.