At atom is made of a nucleus (protons and neutrons) with electrons "orbiting" around it. Quantum mechanics says that these electrons cannot orbit with any energy they like, but must live at discrete, well-defined energy levels. This book has long been recognized as one of the most satisfactory introductions to atomic spectra and their relationship to atomic structure. It is especially valuable to physics and physicał chemists who are specialists in other fields, but require a comprehensive basic knowledge of atomic spectra because of their significance to their own work. A spectrum is a range of frequencies or wavelengths. By the process of refraction, a prism can split white light into it's component wavelengths. However this method is rather crude, so a spectroscope is used to analyze the light passing through the prism more accurately. The diagram to the right shows a simple prism spectroscope. The smaller the difference between distinguishable wavelengths, the higher the resolution of the spectroscope. The observer (shown as an eye in the diagram) sees the radiation passing through the slit as a spectral line. To obtain accurate measurements of the radiation, and electronic device often takes the place of the observer, the device is then called a spectrophotometer. This book is to provide teachers with recent researches that allows students to share. The powerful demonstrations will build a strong foundation for all students.