Introduction

Model of Solids with Impurities

Energy Diagram of Solids

Allowed Energies

Energies with More Impurities

Summarizing Energy Bands

Exploring Light Emissions from Solids with Three Energy Bands

Energy Bands and Fluorescence

Energy Levels in Fluorescence

Bands and Colors of Tubes

Making a Black Light

Applying Fluorscence to Minimize Counterfeit Money