布鲁克红外光谱培训1Introduction_to_FT-IR_c课件.ppt

;傅立叶红外光谱介绍;电磁波;光与分子的作用;振动的种类?;水的红外图;正己烷;正己烷;红外光谱分为三个范围:;如何得到一张图;色散型红外光谱仪;傅利叶变换红外光谱仪原理;source;source;source;source;Mirror motion;Entstehung des Interferogramms;检测器信号;透射光谱;2.) A second interferogram is detected with the sample placed in the sample compartment. The result of the FOURIER transformation is S(ν). S(ν) shows similarities to the reference spectrum R(v), but has lower intensities at the regions the sample absorbs radiation.;The transmission spectrum T(ν) is calculated as the ratio of the sample and reference single channel spectra: T(ν) = S(ν)/R(ν).;Absorbance - Transmission - Why?;Principle layout of FT-IR spectrometer;Layout of an FT-IR spectrometer (TENSOR series);NIR: Source : tungsten lamp Optical material : Quartz Detector: Ge, InGaAs MIR: Source: Globar Optical material: KBr, ZnSe Detector: DTGS, MCT FIR: Source : Globar, Hg lamp Optical material : PE, CsI Detector: DTGS, Bolometer;Fourier Transformation (FT);Data acquisition results in a digitized interferogram, I(x), which is converted into a spectrum by means of the mathematical operation called a Fourier Transform (FT). The general equation for the Fourier Transform is applicable to a continuous signal. If the signal (interferogram) is digitized, however, and consists of N discrete, equidistant points, then the discrete version of the FT (DFT) must be used: S(k . Δ ) = Σ I(n ? Δx) ? exp (i2πk ? n/N) The continuous variables x and have been replaced with n ? Dx and k ? D , representing the n discrete interferogram points and the k discrete spectrum points. The fact that we now have a discrete, rather than continuous, function, and that it is only calculated for a limited range of n (i.e. the measured interferogram has a finite length) leads to important effects known as the picket-fence effect and leakage.;source;添零;截趾函数;Evaluation of IR spectra;定性分析： 1. 鉴定未知物 2. 核对已知物 定量分析 ;未知物的鉴定;不同有几类分子的红外吸收 ;b.) 与标准谱库比较 e.g. by using OPUS/Search;identical material = identical I