A spectrophotometer is a scientific instrument that decomposes light with complex components into spectral lines. Its basic principle is based on the interaction between light and matter. When a photon collides with a substance molecule in a solution, absorption will occur. The absorption of light by a substance is selective, and the amount of a certain substance can be reflected by measuring its absorbance value.
 
Spectrophotometers can be divided into visible spectrophotometers, ultraviolet-visible spectrophotometers, infrared spectrophotometers, fluorescence spectrophotometers and atomic absorption spectrophotometers. So, what is the difference between an atomic absorption spectrometer and an atomic absorption spectrophotometer? Their differences are mainly reflected in three aspects:
 
I. Different principle
1. The principle of atomic absorption spectrometer: the instrument radiates light with characteristic spectral lines of the element to be measured from the light source, which is absorbed by the ground state atoms of the element to be measured in the vapor when it passes through the sample vapor. The content of the element to be measured in the sample is determined by the degree of weakening of the radiation characteristic spectrum. 　　
2. The principle of atomic absorption spectrophotometer: the device that uses the resonance radiation of the element to be measured to measure its absorbance through its atomic vapor is called an atomic absorption spectrophotometer. It has single beam, double beam, double channel, multi-channel and other structural forms, and its basic structure includes light source, atomizer, optical system and detection system.
 
II. Different application
1. Application of atomic absorption spectrometer: It is widely used in the analysis of constant and micro-trace elements in metallurgy, geology, mining, petroleum, light industry, agriculture, medicine, health, food and environmental monitoring.
2. Application of atomic absorption spectrophotometer: it is widely used in the analysis of trace elements in various gases, metal organic compounds, and metal alkoxides.
 
III. Different features
1. Features of atomic absorption spectrometer: simple structure, easy operation and control, relatively low price, good analytical performance, wide application range, fast development speed.
2. Features of atomic absorption spectrophotometer: It has two main advantages, that is,  high sensitivity and good selectivity.