FLAME PHOTOMETRY BASIC CONCEPTS, INSTRUMENTATION, AND The basic principle upon which Atomic Spectroscopy works is based. To determine the concentration of certain metal ions such as sodium, potassium, lithium, calcium, Cesium, etc. and to understand the concept of flame reaction. the serial number of the flame photometer must be quoted. 6. It is important to understand that the principles of flame photometry are such that, over certain. Introduction and Principles. In recent years flame photometry has largely replaced chemical methods for determinations of sodium and potassium. Flame photo-.