Principle of the photomultiplier tube:

The necessary steps of the quantitative determinations methodology are,

• Forming an absorbing species
• Selection of the measurement wavelength
• Controlling factors influencing absorbance
• Validation of Beer and Lambert's law

 A photomultiplier tube is based on the principle of successive rise in the number of electrons. The output signal through photoemission from a series of electrodes known as dynodes is much larger than the original signal.