Infrared band spectrometer is mainly used for analyzing the molecular structure of substances, identifying chemical composition, and studying the interaction between substances and infrared light. The core principle is to achieve qualitative and quantitative analysis of molecular vibrational energy level transitions by detecting the absorption characteristics of substances towards infrared light of different wavelengths.
Chemical bonds in material molecules have different vibrational frequencies due to their different vibrational energy levels. When the frequency of infrared radiation matches the vibrational frequency of the molecule, the molecule absorbs the infrared light at that frequency, resulting in a reduction of the corresponding frequency of light in the transmitted beam. By measuring this absorption situation, the infrared spectrum of the sample can be obtained, and then the molecular structure and chemical composition of the sample can be analyzed.
The working principle of an infrared spectrometer is based on the selective absorption of infrared light by molecular vibrations and rotational energy level transitions. The specific process is as follows:
Infrared light source: emits continuous wavelength infrared light.
Sample absorption: When infrared light passes through the sample, the sample molecules absorb specific wavelengths of infrared light, causing molecular vibration or rotational energy level transitions.
Signal detection: After the unabsorbed light is separated by a monochromator, the detector detects the intensity of different wavelengths of light.
Data processing: By using a data processing system, the detected light intensity signal is converted into the infrared absorption spectrum of the sample. This spectrum reflects the characteristic information of functional groups in molecules, such as chemical bond types, quantities, and molecular structures.
structural composition
Light source: responsible for providing stable infrared radiation, common sources include tungsten lamps, deuterium lamps, and photothermal emission sources, usually using broad-spectrum light sources that can cover the mid infrared to far-infrared bands.
Monochromator: It separates the broad spectrum light emitted by a light source and selectively decomposes it into specific wavelengths of light, usually achieved through prisms or gratings.
Sample Room: located in the middle of the optical path, used to place samples. Different sample pools or racks are used for gas, liquid, and solid samples, where infrared light interacts with the samples.
Detector: converts the light signal transmitted after absorption by the sample into an electronic signal. Common detectors include thermocouple detectors, photodiode detectors, pyroelectric detectors, etc.
Data processing system: Collect signals from detectors, perform data conversion and analysis, convert time-domain signals into frequency-domain spectra through algorithms such as Fourier transform, and generate infrared spectra.