布鲁克红外光谱课件.ppt

傅立叶红外光谱介绍,张远征,13601358075,01068474806-669,Zhang.yuanzheng,傅立叶红外光谱介绍,电磁波,Gamma Ray,X-,Ray,UV,Infrared,Micro Wave,Short Wave,Radio,Waves,Energy,eV,Wavenumber,cm,-1,Wavelength,m,Visible,光与分子的作用,分子激发产生振动,振动的种类,?,伸缩振动,对称伸缩振动,不对称伸缩振动,例如,:,水,变形振动,水的红外图,1500,2000,2500,3000,3500,wavenumber,cm-1,60,65,70,75,80,85,90,95,100,Transmission%,正己烷,50,多不同的振动,正己烷,1000,1500,2000,2500,3000,3500,4000,wavenumber,cm-1,20,40,60,80,100,Transmission%,C-H,stretch,C-H,deformation,指纹区“,红外光谱分为三个范围,:,15.000 cm,-1,4.000 cm,-1,400 cm,-1,5 cm,-1,NIR,MIR,FIR,如何得到一张图,色散型红外光谱仪,傅立叶变换红外光谱仪,色散型红外光谱仪,Detector,Detector,优点,:,-,不需要计算机,缺点速度慢,-,光通量低,=,灵敏度低,(S/N,ratio,),傅利叶变换红外光谱仪原理,光源,动镜,定镜,x,分束器,L,L+,x,x=0,source,Detector,fixed,mirror,M1,x,Beam,splitter,L,L+,x,x=0,例,1:,x,=0,相长干涉,结果,1.Beam part(,定镜,),2.Beam part(,动镜,),source,Detector,fixed,mirror,M1,x,Beam,splitter,L,L+,x,x=1/2,例,2:,x,=,1/2,相消性干涉,0,结果,1.Beam part(,定镜,),2.Beam part(,动镜,),source,Detector,fixed,mirror,M1,x,Beam,splitter,L,L+,x,example 3:,x,=,constructive Interference,0,Resulting signal,1.Beam part(fixed),2.Beam part(movable),x=,source,Detector,fixed,mirror,M1,x,Beam,splitter,L,L+,x,x=3/2,example 4:,x,=,3/2,destructive Interference,0,Resulting signal,1.Beam part(fixed),2.Beam part(movable),Mirror,motion,Intensity,监测器信号,Frequence,Intensity,光源,单色光源,单色光源的调制信号,Entstehung des,Interferogramms,Mirror,motion,Intensity,Resulting,detector,signal,Frequence,Intensity,9,条单一频率的光源,Mirror,motion,Intensity,总和,:,检测器信号,Frequency,Intensity,红外光源,X,moving,mirror,Intensity,干涉图的来源,透射光谱,1.)In,the,empty,sample,compartment,an,Interferogram,is,detected,.,The,result,of,the,FOURIER,transformation,is,R(),.,Fourier-Transformation,500,1000,1500,2000,2500,3000,3500,4000,wavenumber,cm,-1,0.10,0.20,0.30,0.40,Single,channel,intensity,X,moving,mirror,Detector,intensity,2.)A second interferogram is detected with the sample placed in the sample compartment.The result of the FOURIER transformation is,S(),.,S(),shows similarities to the reference spectrum,R(v),but has lower intensities at the regions the sample absorbs radiation.,Fourier-Transformation,500,1000,1500,2000,2500,3000,3500,4000,wavenumber cm,-1,0.10,0.20,0.30,0.40,Single channel intensity,X,moving mirror,Detector intensity,透射光谱,The,transmission,spectrum,T(),is,calculated,as,the,ratio,of,the,sample,and,reference,single,channel,spectra,:,T()=S()/R(),.,500,1000,1500,2000,2500,3000,3500,4000,wavenumber,cm,-1,0.10,0.20,0.30,0.40,Single,channel,intensity,500,1000,1500,2000,2500,3000,3500,4000,wavenumber,cm,-1,40,60,80,100,Transmission%,20,ratio,透射光谱,Absorbance,Transmission-,Why,?,1000,2000,3000,4000,5000,6000,Wavenumber,cm-1,0,20,40,60,80,100,Transmittance,%,1000,2000,3000,4000,5000,6000,Wavenumber,cm-1,0.0,0.2,0.40.6,0.8,1.0,Absorbance,Units,Transmission,Absorbance,T()=S()/R(),Lambert-Beers,law,:,AB=-log(S()/R(),AB=,c,b,Principle,layout,of,FT-IR,spectrometer,Source,Moving,mirror,Fixed mirror,x,Beamsplitter,L,L+,x,x=0,Layout of an FT-IR,spectrometer,(TENSOR,series,),Electronic,Source,compartment,Sample,compartment,Sample,position,Detector,Interferometer,compartment,Aperture,wheel,Filter,wheel,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,Differences,between,NIR,MIR,FIR,Optical,components,:,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,.,)=,I(n,x,),exp(i2k,n/N),The continuous variables x and have been replaced with n,D,x,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.,The Fourier Transform,source,detector,movable,mirror,M2,fixed,mirror,M1,x,Beam,splitter,L,L+,x,x=0,高光谱分辨,低光谱分辨,添零,The picket-fence effect occurs if the,interferogram,contains frequency components which do not exactly coincide with the data point positions,k,.,in the spectrum.The effect can be thought of as viewing the spectrum through a picket fence,thereby hiding those frequencies that are behind the pickets,i.e.between the data point positions k,.,.In the worst case,if a frequency component is exactly between two sampling positions,a signal reduction of 36%can occur.,The picket-fence effect can be reduced by adding zeros to the end of the,interferogram,(zero filling),before the DFT is performed.This interpolates the spectrum,increasing the number of points per,wavenumber,.The increased number of frequency sampling positions reduces the error caused by the picket-fence effect.Generally,the original,interferogram,size should always be at least doubled by zero filling,i.e.zero filling factor(ZFF)of two is chosen.Zero-filling interpolates using the instrument line-shape,and in most cases is therefore superior to,polynominal,or,spline,interpolation methods that are applied in the spectral domain.,1,796,1,798,1,800,1,802,1,804,1,806,1,808,Wavenumber,cm-1,0.35,0.40,0.45,0.50,0.55,Single channel,1,796,1,798,1,800,1,802,1,804,1,806,1,808,Wavenumber,cm-1,0.35,0.40,0.45,0.50,0.55,Single channel,Zero-filling factor 2,Zero-filling factor 8,截趾函数,In a real measurement,the,interferogram,can only be measured for a finite distance of mirror travel.The resulting,interferogram,can be thought of as an infinite length,interferogram,multiplied by a boxcar function that is equal to 1 in the range of measurement and 0 elsewhere.This sudden truncation of the,interferogram,leads to a,sinc,()(i.e.sin()/)instrumental,lineshape,.For an infinitely narrow spectral line,the peak shape is shown at the top of the figure on the right.The oscillations around the base of the peak are referred to as“ringing”,or“leakage”.,The solution to the leakage problem is to truncate the,interferogram,less abruptly.This can be achieved by multiplying the,interferogram,by a function that is 1 at the,centerburst,and close to 0 at the end of the,interferogram,.This is called,apodization,and the simplest such function is a ramp,or“triangular,apodization,”.,The choice of a particular,apodization,function depends on the objectives of the measurement.If the maximum resolution of 0.61/,L is required,then boxcar,apodization,(i.e no,apodization,)is used.If a resolution loss of 50%(compared to the maximum resolution of 0.61/,L,)can be tolerated,the HAPP-GENZEL or,even better,3-Term BLACKMAN-HARRIS function is recommended.,A,BOXCAR(no,apodization,),B,Triangular,C,Trapezoidal,D,HAPP-GENZEL,E,3-TERM BLACKMAN-HARRIS,Evaluation of IR spectra,定性分析：,1.,鉴定未知物,2.,核对已知物,定量分析,光谱评价,未知物的鉴定,a),通过光谱解析推出分子结构,500,1,000,1,500,2,000,2,500,3,000,3,500,4,000,Wavenumber,/cm,-1,40,60,80,100,Transmission%,20,不同有几类分子的红外吸收,烷烃,烯烃,芳香烃,内酯,卤化物,羧酸盐,酸酐,b.),与标准谱库比较,e.g.by using OPUS/Search,未知物的鉴定,identical material =identical IR spectrum,-What you have:,sample,-What you need:,reference library,-What you do:,comparison with reference library,-What you get:,identification,验证已知物,2.)Calculate average spectrum&threshold values,3.)Library structure&validation,1.)Measure reference sample,Wavenumber,/cm,-1,Absorbance,Wavenumber,/cm,-1,Absorbance,Reference library structure,Identified,sample:,material X,1.)Measure new samples,2.)Compare with library,Identifying new samples,3.)Identify material,-What you have:,sample,What you need:,calibration set,-What you do:,comparison with calibration set,-What you get:,concentration value,There are two different forms of calibration:,Univariate,calibration(OPUS),-Correlates just one piece of spectral information(e.g.peak height or peak area)with the reference values of the calibration set.,Multivariate calibration(OPUS/QUANT),-Correlates considerably more spectral information,-higher degree of precision,-reduced chance of error,OPUS/QUANT uses the Partial Least Squares(PLS)Method.,X,Analysis,1,2,3,4,Absorbance,Concentration,X,1,3,2,4,Absorbance,Wavelength,CalibrationQuantitative evaluation of spectra,2.)Build calibration set(Quant Method),3.)Validate calibration set,1.)Measure calibration spectra,Wavenumber,/cm,-1,Absorbance,Setup of a Quant Method,1,2,3,4,Absorbance,Concentration,Concentration:58 vol.%,1.)Measure sample,2.)Compare with calibration set,Determine quantitative results(e.g.concentration values),3.)Result,FT-IR,measurements,Enter,sample name,Start the,background and,sample,measurement,Sampling bandwidth in,interferogram,domain,The FT of a measured,interferogram,yields a complex spectrum.The aim of the phase correction is to calculate the real spectrum,.,Interpolation of the spectrum by adding zeros to the end of the,interferogram,Defines the separation of adjacent peaks,Acquisition mode,single sided,double sided,fast backward,forward and backward,If you have any further questions about IR spectroscopy,please contact the application team of Bruker Optics:,Europe,:,Bruker Optik GmbH,Rudolf-Plank-,Str,.27,76275 Ettlingen,Germany,Phone:[phone],Fax:[phone],infobrukeroptics.de,North America,:,Bruker Optics Inc,19 Fortune Drive,Billerica,MA 01821,USA,Phone:[phone],Fax:[phone],info,Asia,:,Bruker Optik Asia Pacific Ltd.,Unit 601,6/F,Tower 1,Enterprise Square,No.9,Sheung,Yuet,Road,Hong Kong,Phone:[phone],Fax:[phone],asiapacific.hk,