Gas analyzer spectroscopy refers to the use of spectroscopic techniques for the analysis of gases. These techniques rely on the interaction between light and gas molecules to identify and quantify the chemical composition of gas samples. The working principle involves measuring the absorption, emission, or scattering of light by gas molecules at specific wavelengths, which provides information about the presence and concentration of individual components in the gas mixture.

Here are the working principles and types of gas analyzer spectroscopy techniques:

1. Absorption Spectroscopy:

   • Absorption spectroscopy involves measuring the attenuation of light as it passes through a gas sample.
   • The gas molecules absorb light at specific wavelengths corresponding to their molecular structure and energy levels.
   • By measuring the decrease in intensity of the transmitted light at these absorption bands, the concentration of individual gas components can be determined.
   • Common techniques include:
     • Infrared (IR) Spectroscopy: Measures the absorption of infrared radiation by gas molecules. Fourier-transform infrared (FTIR) spectroscopy is a widely used technique for gas analysis.
     • UV-Visible Spectroscopy: Measures the absorption of ultraviolet (UV) and visible light by gas molecules. It is primarily used for analyzing trace gases and atmospheric pollutants.

2. Emission Spectroscopy:

   • Emission spectroscopy involves measuring the emission of light by gas molecules when they are excited by an external energy source.
   • The emitted light is characteristic of the specific electronic transitions or molecular vibrations of the gas molecules.
   • By analyzing the emitted spectrum, the presence and concentration of gas components can be identified.
   • Techniques include:
     • Fluorescence Spectroscopy: Measures the fluorescence emitted by gas molecules following absorption of light at shorter wavelengths.
     • Laser-Induced Breakdown Spectroscopy (LIBS): Uses a high-energy laser pulse to vaporize and excite gas molecules, producing a characteristic emission spectrum that can be analyzed.

3. Scattering Spectroscopy:

   • Scattering spectroscopy involves measuring the scattering of light by gas molecules at specific wavelengths.
   • The scattering patterns are influenced by the size, shape, and refractive index of the gas molecules.
   • By analyzing the scattered light, information about the concentration and properties of gas molecules can be obtained.
   • Techniques include:
     • Raman Spectroscopy: Measures the inelastic scattering of light by gas molecules, providing information about molecular vibrations and rotational transitions.

Gas analyzer spectroscopy techniques can be further classified based on the specific interactions between light and gas molecules, as well as the detection methods employed. These techniques offer high sensitivity, selectivity, and accuracy for the analysis of gas samples in various applications, including environmental monitoring, industrial process control, combustion analysis, and research.