Explain the theory, instrumentation and applications of flame photometry.

9 a]Explain the theory, instrumentation and applications of flame photometry.

Theory:

When a solution containing metallic salt is sprayed into flame, the solution dries out by leaving a fine residue of neutral atoms. These neutral atoms absorb the thermal energy of the flame and get excited to their higher energy state and thereafter return to ground state. During return to ground state, the excited atoms lose the absorbed energy by emitting radiation of specific wavelength. This wavelength of radiation emitted is specific for every element, while the intensity of emitted radiation depends on the concentration of element ( E ∝ C) where E is emission intensity, C is concentration.

Instrumentation:

A simple flame photometer is shown in figure.

1. An atomizer (Nebulizer)
2. The burner system
3. An optical system
4. A photocell
5. Amplifier

Application:

1. Flame photometry is primarily used for the analysis of elements which have characteristic emission. E.g. Na, K etc.
2. It is used for analysis of alkali and alkaline earth metals.
3. It is used in the analysis of soil.