1、Designation: E131 10 (Reapproved 2015)Standard Terminology Relating toMolecular Spectroscopy1, 2This standard is issued under the fixed designation E131; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.2. Referenced D
3、ocuments2.1 ASTM Standards:3E135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE168 Practices for General Techniques of Infrared Quanti-tative Analysis (Withdrawn 2015)4E204 Practices for Identification of Material by InfraredAbsorption Spectroscopy, Using the AS
4、TM Coded Bandand Chemical Classification Index (Withdrawn 2014)4E284 Terminology of AppearanceE386 Practice for Data Presentation Relating to High-Resolution Nuclear Magnetic Resonance (NMR) Spec-troscopyE456 Terminology Relating to Quality and Statistics2.2 Other Documents:5ISO Guide 301981 (E) Ter
5、ms and definitions used in con-nections with reference materials3. Terminologyabsorbance, Athe logarithm to the base 10 of the reciprocalof the transmittance, (T).A 5 log101/T! 52log10T (1)DISCUSSIONIn practice the observed transmittance must be substi-tuted for T. Absorbance expresses the excess ab
6、sorption over that of aspecified reference or standard. It is implied that compensation hasbeen effected for reflectance losses, solvent absorption losses, andrefractive effects, if present, and that attenuation by scattering is smallcompared with attenuation by absorption.Apparent deviations from t
7、heabsorption laws (see absorptivity) are due to inability to measureexactly the true transmittance or to know the exact concentration of anabsorbing substance.absorption banda region of the absorption spectrum inwhich the absorbance passes through a maximum.absorption coefficient, a measure of absor
8、ption of radiantenergy from an incident beam as it traverses an absorbingmedium according to Bouguers law, P/Po= eb.DISCUSSIONIn IRS, is a measure of the rate of absorption ofenergy from the evanescent wave.absorption parameter, athe relative reflection loss perreflection that results from the absor
9、ption of radiant energyat a reflecting surface: a=1R, and R = the reflectedfraction of incident radiant power.absorption spectruma plot, or other representation, ofabsorbance, or any function of absorbance, againstwavelength, or any function of wavelength.absorptivity, a the absorbance divided by th
10、e product of theconcentration of the substance and the sample pathlength,a=Abc.The units of b and c shall be specified.DISCUSSION1The recommended unit for b is the centimetre. Therecommended unit for c is kilogram per cubic metre. Equivalent unitsare g/dm3, g/L, or mg/cm3.DISCUSSION2The equivalent I
11、UPAC term is “specific absorptioncoefficient.”absorptivity, molar, the product of the absorptivity, a, andthe molecular weight of the substance.DISCUSSIONThe equivalent IUPAC term is “molar absorption coef-ficient.”acceptance angle, nfor an optical fiber, the maximum angle,measured from the longitud
12、inal axis or centerline of the fiberto an incident ray, within which the ray will be accepted fortransmission along the fiber by total internal reflection.DISCUSSIONIf the incidence angle exceeds the acceptance angle,optical power in the incident ray will be coupled into leaky modes orrays, or lost
13、by scattering, diffusion, or absorption in the cladding. Fora cladded step-index fiber in the air, the sine of the acceptance angle isgiven by the square root of the difference of the squares of the refractiveindexes of the fiber core and the cladding, that is, by the relation asfollows:1This termin
14、ology is under the jurisdiction of ASTM Committee E13 onMolecular Spectroscopy and Separation Science and is the direct responsibility ofSubcommittee E13.94 on Terminology.Current edition approved May 1, 2015. Published June 2015. Originallyapproved in 1957. Last previous edition approved in 2010 as
15、 E131 10. DOI:10.1520/E0131-10R15.2For other definitions relating to nuclear magnetic resonance, see Practice E386.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to t
16、he standards Document Summary page onthe ASTM website.4The last approved version of this historical standard is referenced onwww.astm.org.5Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 B
17、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1sin A 5 = n122 n22(2)where A is the acceptance angle and n1and n2are the refractive in-dexes of the core and cladding, respectively. If the refractive index is afunction of distance from the center of the core, as in the
18、case ofgraded index fibers, then the acceptance angle depends on the distancefrom the core center. The acceptance angle is maximum at the center,and zero at the core-cladding boundary. At any radius, r, the sine of theacceptance angle of a graded index fiber is defined in compliance withthat of a st
19、ep-index fiber as follows:sin Ar5 =n122 n22(3)where Aris the acceptance angle at a point on the entrance face at adistance, r, from the center, nris the refractive index of the core at aradius, r, and n2is the refractive index of the cladding. In air, sin Aand sin Arare the numerical apertures. Unle
20、ss otherwise stated, accep-tance angles and numerical apertures for fiber optics are those for thecenter of the endface of the fiber, that is, where the refractive index,and hence the numerical aperture, is the highest.accuracythe closeness of agreement between an observedvalue and an accepted refer
21、ence value (see TerminologyE456).DISCUSSIONThe term accuracy, when applied to a set of observedvalues, will be a combination of a random component and a commonsystematic error or bias component. Since in routine use, randomcomponents and bias components cannot be completely separated, thereported “a
22、ccuracy” must be interpreted as a combination of these twocomponents.active fiber optic chemical sensor, na fiber optic chemicalsensor in which a transduction mechanism other than theintrinsic spectroscopic properties of the analyte is used tomodulate the optical signal.DISCUSSIONExamples include a
23、pH sensor composed of a chemicalindicator substance whose color changes with pH, and an oxygensensor coupled to an optical fiber bearing a chemical indicator whosefluorescence intensity depends on oxygen concentration.aliasingthe appearance of features at wavenumbers otherthan their true value cause
24、d by using a sampling frequencyless than twice the highest modulation frequency in theinterferogram; also known as “folding.”analytical curvethe graphical representation of a relationbetween some function of radiant power and the concentra-tion or mass of the substance emitting or absorbing it.analy
25、tical wavelengthany wavelength at which an absor-bance measurement is made for the purpose of the determi-nation of a constituent of a sample.angle of incidence, the angle between an incident radiantbeam and a perpendicular to the interface between twomedia.anti-Stokes line (band)a Raman line (band)
26、 that has afrequency higher than that of the incident monochromaticbeam.aperture of an IRE, Athat portion of the IRE surface thatcan be utilized to conduct light into the IRE at the desiredangle of incidence.apodizationmodification of the ILS function by multiplyingthe interferogram by a weighting f
27、unction the magnitude ofwhich varies with retardation.DISCUSSIONThis term should strictly be used with reference to aweighting function whose magnitude is greatest at the centerburst anddecreases with retardation.attenuated total reflection (ATR)reflection that occurswhen an absorbing coupling mecha
28、nism acts in the processof total internal reflection to make the reflectance less thanunity.DISCUSSIONIn this process, if an absorbing sample is placed incontact with the reflecting surface, the reflectance for total internalreflection will be attenuated to some value between zero and unity (OR1) in
29、 regions of the spectrum where absorption of the radiantpower can take place.attenuation index, a measure of the absorption of radiantenergy by an absorbing material. is related to the absorp-tion coefficient by: n = co/4, where co= the speed oflight in vacuo, = the frequency of radiant energy, andn
30、 = the refractive index of the absorbing medium.backgroundapparent absorption caused by anything otherthan the substance for which the analysis is being made.baselineany line drawn on an absorption spectrum to estab-lish a reference point representing a function of the radiantpower incident on a sam
31、ple at a given wavelength.basic NMR frequency, 0the frequency, measured in hertz(Hz), of the oscillating magnetic field applied to inducetransitions between nuclear magnetic energy levels.bathochromic shift, nchange of a spectral band to longerwavelength (lower frequency) because of structural modif
32、i-cations or environmental influence; also known as “redshift.”beamsplittera semireflecting device used to create, andoften to recombine, spatially separate beams.DISCUSSIONBeamsplitters are often made by depositing a film of ahigh refractive index material onto a flat transmitting substrate with an
33、identical compensator plate being held on the other side of the film.beamsplitter efficiencythe product 4RT, where R is thereflectance and T is the transmittance of the beamsplitter.Beers lawthe absorbance of a homogeneous sample con-taining an absorbing substance is directly proportional to theconc
34、entration of the absorbing substance (see also absorp-tivity )biasa systematic error that contributes to the differencebetween a population mean of the measurements or testresults and an accepted or reference value (see TerminologyE456).DISCUSSIONBias is determined by the following equation:bias 5 e
35、 51n(i51nei(4)where:n = the number of observations for which the accuracy isdetermined,ei= the difference between a measured value of a propertyand its accepted reference value, ande = the mean value of all the eI.E131 10 (2015)2Bouguers lawthe absorbance of a homogeneous sample isdirectly proportio
36、nal to the thickness of the sample in theoptical path.DISCUSSIONBouguers law is sometimes also known as Lambertslaw.boxcar truncationidentical effective weighting of all pointsin the measured interferogram prior to the Fourier transform;all points outside of the range of the measured interferogramta
37、ke a value of zero.bufferin fiber optics, see fiber optic buffer.bulk reflectionreflection in which radiant energy is returnedexclusively from within the specimen.DISCUSSIONBulk reflection may be diffuse or specular.centerburstthe region of greatest amplitude in an interfero-gram.DISCUSSIONFor unchi
38、rped or only slightly chirped interferograms,this region includes the “zero path difference point” and the “zeroretardation point.”certified reference material, na reference material, thecomposition or properties of which are certified by arecognized standardizing agency or group.DISCUSSIONA certifi
39、ed reference material produced by the NationalInstitute of Standards and Technology (NIST) is designated a StandardReference Material (SRM).chemical shift (NMR), the defining equation for is thefollowing: 5R3106(5)where Ris the frequency with which the reference sub-stance is in resonance at the mag
40、netic field used in the ex-periment and is the frequency difference between the ref-erence substance and the substance whose chemical shift isbeing determined, at constant field. The sign of is to bechosen such that shifts to the high frequency side of the ref-erence shall be positive.DISCUSSIONIf t
41、he experiment is done at constant frequency (fieldsweep) the defining equation becomes 5R3S1 2RD3106(6)chirpingthe process of dispersing the zero phase differencepoints for different wavelengths across the interferogram, sothat the magnitude of the signal is reduced in the short regionof the interfe
42、rogram where all wavelengths would otherwiseconstructively interfere.cladsee cladding.cladding, nof an optical fiber, a layer of a optically trans-parent lower refractive index material in intimate contactwith a core of higher refractive index material used toachieve total internal reflection.DISCUS
43、SIONThe cladding confines electromagnetic waves to thecore, provides some protection to the core, and also transmits evanes-cent waves that usually are bound to waves in the core.concentration, cthe quantity of the substance contained in aunit quantity of sample.DISCUSSIONFor solution work, the reco
44、mmended unit of concen-tration is grams of solute per litre of solution.core, nof an optical fiber, the center region of an opticalwaveguide through which radiant energy is transmitted.DISCUSSIONIn a dielectric waveguide such as an optical fiber, therefractive index of the core must be higher than t
45、hat of the cladding.Most of the radiant energy is confined to the core.correlation coefficient (r)a measure of the strength of thelinear relationship between X and Y, calculated by theequation:rxy5(i51nXiYi!(i51nXi2!1/2(i51nYi2!1/2(7)where:n = the number of observations in X and Y.DISCUSSIONXiand Yi
46、are any two mean corrected variables. For thesimple linear regression only,rxy5 R 5 sign of b1!R2!1/2(8)where:R2= the coefficient of multiple determination.critical angle, cthe angle whose sine is equal to the relativerefractive index for light striking an interface from thegreater to the lesser ref
47、ractive medium: c= sin1n21, wheren21= the ratio of the refractive indices of the two media.DISCUSSIONTotal reflection occurs when light is reflected in themore refractive of two media from the interface between them at anyangle of incidence exceeding the critical angle.depth of penetration, dpin int
48、ernal reflection spectroscopy,the distance into the less refractive medium at which theamplitude of the evanescent wave is e1(that is, 36.8 %) ofits value at the surface:dp512 sin2 2 212!1/2(9)where: n21=n2/n1= refractive index of sample divided bythat of the IRE; 1= n1= wavelength of radiant energy
49、 inthe sample; and = angle of incidence.derivative absorption spectruma plot of rate of change ofabsorbance or of any function of absorbance with respect towavelength or any function of wavelength, against wave-length or any function of wavelength.difference absorption spectruma plot of the differencebetween two absorbances or between any function of twoabsorbances, against wavelength or any function of wave-length.diffuse reflectionreflection in
