3. 中红外的波长范围
the region of IR
中红外范围：400~4000cm-1
Mid infrared region:400~4000cm-1
Mid-infrared range: 400~4000cm-1
Mid infrared region:400~4000cm-1
4. 分子的振动频率 The vibration of frequency of molecule
分子的振动频率v与化学键的力常数k与分子质量m有关，振动力常数k越大，或者分子
质量越小，分子振动频率越高。
The vibration frequencyⅴis related to the force constant k and mass m,the force cons
tant is more large or the mass is more slight result in a highter frequency.
The vibration frequency v of the molecule is related to the force constant k of the chemical bond and the molecular ma
ss m, and the larger the vibration force constant k, or the smaller the molecular mass, the higher the molecular vibratio
n frequency. The vibration frequencyⅴis related to the force constant k and mass m,the force constant is more large o
r the mass is more slight result in a highter frequency.
5. 分子能级的跃迁 the transition of vibration level
分子吸收与其振动频率相等的红外光时，分子得到相应的能量（E振=E红=hυ)后,会发
生振动能级的跃迁。
When molecule absorb infrared radiation that frequeny equal to molecular vibration freque
ncy，obtain the energy (E=hv），and then occur the transition of vibration level.
When the molecule absorbs infrared light equal to its vibration frequency, the corresponding energy (E vibratio
n = E red = hυ) of the molecule will occur after the vibration energy level transition.
6. 分子能级的跃迁 the transition of vibration level
当分子吸收E=hv的能量，振动能级从n=0向n=1跃迁，产生基频吸收
峰，当分子吸收2E=2hv的能量，振动能级从n=0向n=2跃迁，产生
倍频吸收峰。
The molecule absorbs infrared light of an energy equal to hv(fundame
ntal),and at 2hv(overtone).
7. 产生红外吸收的条件Selection Rules for Infrared Activity
d
q
分子吸收红外光，发生能级的跃
迁，分子的偶极距u必须发生改
变。
红外光的频率必须与分子自身振
动频率相匹配，也就是说辐射光
子具有的能量与发生振动跃迁所
需的跃迁能量相等。
To absorb energy,the dipole must change w
hen the transition occurs
The frequency of the infrared radiation mus
t be identical to the (theoretical) frequency
of the vibration of the molecule. We call thi
s resonance.
8. 样品对红外光的吸收 Absorption of IR
当红外光照射到样品时，特定频率的红外光被样品吸收。 特定频率指红外光
的频率等于样品中分子的振动频率.
When IR radiation transmitted the sample,the IR of the specific frequency be abso
rbed by sample,the frequency of the IR radiation must be identical to the frequen
cy of the vibration of molecule in sample.
9. 官能团区和指纹区 The region of funcational groups and fingerprint
官能团区（4000-1350 cm-1 ) ：与一定
结构单元相联系的，只要有这个官能团，
就会有官能团的特征吸收峰。
指纹区(1350 650 cm-1 ) ：较复杂，
与整个分子的结构有关。当分子结构稍
有不同时，该区的吸收就有细微的差异，
比如苯环上取代甲基的位置。
Funcational groups region(4000~1350cm-1):
It is linked to funcational groups in molecule.
Fingerprint region(1350~650cm-1):
It is related to whole molecular structure.
1000
1500
2000
2500
3000
3500
Wavenumbers (cm-1)
Fingerprint region
Functional groups……...
12. 干涉仪 The interferometer
红外光进入干涉仪，50%的光分透过束器，50%的光被分束器反射，分别照射到动镜和
定镜，再被定镜和动静反射到分束器，再次半透半反后形成干涉光。
IR radiation passed into beamsplitter,50% of IR radiation be transmitted to the moving
mirror,50% be reflected to the fix mirror. The two beams are refected from these two mi
rrors,returning to the beam splitter where they recombine and interfere.
Source
13. 傅里叶变换红外光谱仪 Fourier-Transform Infrared Spectrometers
傅里叶变换红外光谱仪的基本理念是通过形成干涉光产生干
涉图。通过对频率进行积分，得到在某一光程差上干涉光能
量的强度。再通过傅里叶逆变换得到得到某一频率干涉光的
强度。
傅里叶变换公式
傅里叶逆变换
红外光进入干涉仪形成干涉光，穿过样品达到探测器。
Fourier-transform infrared spectroscopy is based on the idea
of the Interference of radiation between two beams to yield a
n interferogram. The interferogram is a signal produced as a f
unction of the change of pathlength between the two beams.
The two domains of distance and frequency are interconvertib
le by the mathematical method of Fourier-transformation.
The radiation emerging from the source and passed through a
n interferometer to the sample before reaching a detector.
14. 干涉图和光谱图 Interferogram and spectrum
计算机对频率ⅴ进行积分
To integrate the frequency,
得到某一光程差位置δ所有频率干涉光强
度
obtain the intensity of power at particular p
athlenth,
再经过傅里叶逆运算
得到某一频率ⅴ的红外光谱图强度
And then obtain the intensity of power at
particular frequency by the mathematic
al method of Fourier-transformation.
干涉图 interferogram
光谱图 spectrum
15. 有关傅立叶变换红外光谱仪的几
个基本概念 The term of IR spectrometer
波数 wave number
波数是波长的倒数。
Wave number is reciprocal of wavelength.
分辨率 resolution
分辨力是指分辨相邻谱线的能力
The resolution is ability of identifying adjacent
absorption peak.
信噪比 S/N
仪器的信噪比是信号与噪声的比值.与扫描次数，
分辨率，红外光通量成正比。
S/N is the ratio of signal to noise，have relation of
direct ratio with scanning times,resolution and
throughput . results with different resolusion
/
1
：cm-1
16. 傅里叶变换红外光谱仪的优点 Advanta
ges
Why would we rather use FT instruments than di
spersive ones? There are three major advantag
es of FT instruments:
1 Multiplex: since all wavelength are measured s
imultaneously ,the measurement time is greatly
reduced.
2 Throughput: FT instruments don’t use slits, th
erefore the amount of light entering into the ins
trument is much larger, and the measurement is
less sensitive to noise.
3. Connes’: since we use an extremely accurate l
aser for the position determination of the mirror,
the precision is very high, better than 0.01 cm-1.
This is better for quantitative analysis and librar
y searching.
为什么我们用傅里叶红外代替传统
的光栅红外？
1.多元化优点 (Felgett’s)
所有波长同时测量
2.高光通量优点 (Jacquinot’s)
更高的能量通过 (更大的光栏)
不需要分光，信号强，灵敏度很高
3.高精度优点 (Connes’)
内部校正源自He-Ne 激光 (精度 = 0.
01 cm-1)
17. WQF-530/520A傅立叶变换红外光谱仪
FTIR Spectrometer
波数范围：7800cm-1~350cm-1
分辨率：530型：优于0.85cm-1
520A型：优于0.5 cm-1
波数精度：±0.01 cm-1
信噪比： 520A型优于15000：1,
530型优于20000：1 （RMS值，在2100 cm-1 处，
4 cm-1分辨率，DTGS探测器，1分钟数据采集。）
分束器：KBr基片镀锗
探测器：DTGS
光源：高强度空气冷却红外光源
符合FDA21CFR PART 11: 具有访问控制、权限分配、审计追
踪和电子签名等功能，并符合GMP/GLP和CFDA发布的
《计算机化系统》的要求。
WQF-530型
Spectral range:7800cm-1~350cm-1
Resolution:
better than 0.85cm-1(WQF-530)
better than 0.5cm-1(WQF-520A)
Wavenumber accuracy:±0.01cm-1
Signal to noise ratio: 520A better than 15
000:1, 530 better than 20000:1
Beam splitter:Ge be coated on Kbr
Detector:DTGS
IR source:air-cooled,high efficiency
WQF-520A型
18. 红外附件 Accessory
气体池 Gas Cell
用于测试气体样品. Be used to test gas.
液体池 Liquid Cell
用于测试液体样品. Be used to test liquid.
漫反射附件 Diffuse reflectance
用于测试粉末状固体。（如果这种粉末不能被研磨的很细＜0.2um）
Be used for powder analysis,if the diameter of particle of sample
is not less than 0.2um through being grinded.
衰减全反射附件 Attenuated Total Reflection(ATR)
适用于橡胶，粘稠液体，柔韧性固体分析。
Horizontal ATR is suitbale for testing rubber,sticky liqiud and
pliable solid.
21. 漫反射附件 Diffuse reflectance
当光束入射至粉末状的晶面层时，一部分光在表层各晶粒
面产生镜面反射；另一部分光则折射入表层晶粒的内部，
经部分吸收后射至内部晶粒界面，再发生反射、折射吸收。
如此多次重复，最后由粉末表层朝各个方向反射出来，这
种辐射称为漫反射光，
由于反射峰通常很弱，同时，它与吸收峰基本重合，仅仅
使吸收峰稍有减弱而不至于引起明显的位移，对固体粉末
样品的镜面反射光及漫反射光同时进行检测可得到其漫反
射光谱。
When the incident light get to sample suer
face,may be partly reflected regularly,partl
y scattered diffusely,and partly enter the s
ubstrate. The latter part may undergo abs
orption with particles,emerge at the samp
le surface and intermingle with reflected p
arts.
Specular Reflectance
Diffuse Reflect
ance
22. 衰减全反射附件 Attenuated Total Reflection(ATR)
光束进入晶体，当入射角大于临界角，
光束在晶体内部发生全反射。当样品和
晶体紧密接触的时候，一部光被样品吸
收。
A beam of radiation entering a crystal will under
go total internal refection when the angle of inci
dence at the interface between the sample and
crystal is greater than the critical angle ,where t
he latter is a function of the refractive indices of
the two surfaces .the beam penetrates a fractio
n of a wavelength beyond the reflecting surface,
when a material that selectively absorbs radiatio
n is in close contact with the reflecting surface ,t
he beam loses energy at the wavelength where t
he material absorbs.
23. 制样方法 Sampling method
Kbr压片法
将1~2mg试样与200mg纯KBr研细均匀，
置于模具中，用5~10MPa压力在油压机
上压成透明薄片。试样和KBr都应经干
燥处理，研磨到粒度小于2微米，以免
散射光影响。
Kbr discs for solids
To mix a solid sample with dry Kbr powder. The lit
tle sample is needed and around 1 to 2mg sample
with about 200mg Kbr.
Place mixed powder in the mould,and subjected t
o a pressure of 8~10MPa with one
Minute.
Sample and Kbr must be dry,to avoid the effect fr
om water.
The diameter of particles must be less than 0.2um,
in order to avoid scattering results.
