红外光谱仪

分子的每一运动状态都具有一定能量，它们分别是：转动能、电子的运动能、组成分子的原子振动能和平动能。当红外辐射与物质分子有选择性地相互作用时，分子就吸收或发射一定频率的红外辐射。振动能级的吸收或发射对应于中红外、近红外波段；转动能级的吸收和发射在远红外波段；红外光谱仪就是记录这种吸收或发射电磁波的仪器，得到的是以等间隔波数为横坐标、吸光度或透过度为纵坐标表示的谱图即红外光谱图。不同物质对红外辐射的吸收不同，其红外光谱图也不相同；吸收光谱的谱带强度服从朗伯－比尔定律，这些便是红外光谱进行定性定量及物质结构分析的理论根据。发射光谱是以样品为红外辐射源，来测量样品的红外发射光谱。发射强度取决于发射温度和物质结构。物质的发射谱带同样也是吸收谱带。利用物质吸收或发射红外光谱原理，可以对物质进行定性定量及结构分析。从红外光源发出的红外光，经迈克尔逊干涉仪干涉调频后入射至样品，透过(或反射)后到达检测器，透过光包含了样品对每一频率的吸收信息，将检测器检测到的光强(干涉图)信号输入计算机进行傅里叶变换处理，结果以红外光谱图的形式输出，并由计算机通过接口对仪器(光学台)实施控制。为了向吉林省提供公正准确权威的傅里叶变换红外光谱仪的第三方校准数据，特开展此校准项目。Every motion state of a molecule has a certain amount of energy, which includes rotational energy, electronic motion energy, vibrational energy of the atoms that make up the molecule, and translational kinetic energy. When infrared radiation interacts selectively with the molecules of a substance, the molecules will absorb or emit infrared radiation at a specific frequency. Absorption or emission corresponding to vibrational energy levels falls within the mid-infrared and near-infrared bands, while that corresponding to rotational energy levels lies in the far-infrared band. An infrared spectrometer is an instrument that records such absorbed or emitted electromagnetic waves, and the resulting spectrum is the infrared spectrum, with evenly spaced wavenumbers as the abscissa and absorbance or transmittance as the ordinate. Different substances exhibit different infrared radiation absorption behaviors, leading to distinct infrared spectra; the band intensities of absorption spectra follow the Lambert-Beer Law, which forms the theoretical basis for qualitative, quantitative, and structural analysis of substances using infrared spectroscopy. Emission spectroscopy measures the infrared emission spectrum of a sample by taking the sample itself as the infrared radiation source. The emission intensity depends on the emission temperature and the substance's structure, and the emission bands of a substance are identical to its absorption bands. By leveraging the principles of infrared absorption and emission spectroscopy, qualitative, quantitative, and structural analysis of substances can be performed. Infrared light emitted from an infrared source is interferometrically frequency-modulated by a Michelson interferometer before being incident onto the sample. After passing through (or being reflected by) the sample, the light reaches the detector. The transmitted light contains information about the sample's absorption at each frequency. The light intensity (interferogram) signal detected by the detector is input into a computer for Fourier transform processing, and the results are output in the form of an infrared spectrum. The computer also controls the instrument (optical bench) via an interface. This calibration project was carried out to provide impartial, accurate, and authoritative third-party calibration data for Fourier-transform infrared spectrometers in Jilin Province.