ASTM_E_1683_-_02_2014e1.pdf

Designation:E168302(Reapproved 2014)1Standard Practice forTesting the Performance of Scanning RamanSpectrometers1This standard is issued under the fixed designation E1683;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEUnits statement was inserted in Section 1.2 editorially in June 2014.1.Scope1.1 This practice covers routine testing of scanning Ramanspectrometer performance and to assist in locating problemswhen performance has degraded.It is also intended as a guidefor obtaining and reporting Raman spectra.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.For specificprecautions,see 7.2.1.1.4 Because of the significant dangers associated with theuse of lasers,ANSI Z136.1 should be followed in conjunctionwith this practice.2.Referenced Documents2.1 ASTM Standards:2E131 Terminology Relating to Molecular SpectroscopyE1840 Guide for Raman Shift Standards for SpectrometerCalibration2.2 ANSI Standard:3Z136.1 Safe Use of Lasers3.Terminology3.1 Terminology used in this practice conforms to thedefinitions in Terminology E131.4.Significance and Use4.1 A scanning Raman spectrometer should be checkedregularly to determine if its condition is adequate for routinemeasurements or if it has changed.This practice is designed tofacilitatethatdeterminationand,ifperformanceisunsatisfactory,to identify the part of the system that needsattention.These tests apply for single-,double-,or triplemono-chromator scanning Raman instruments commercially avail-able.They do not apply for multichannel or Fourier transforminstruments,or for gated integrator systems requiring a pulsedlaser source.Use of this practice is intended only for trainedoptical spectroscopists and should be used in conjunction withstandard texts.5.Apparatus5.1 LaserAmonochromatic,continuous laser source,suchas an argon,krypton,or helium-neon laser,is normally used forRaman measurements.The laser intensity should be measuredat the sample with a power meter because optical componentsbetween the laser and sample reduce laser intensity.A filteringdevice should also be used to remove non-lasting plasmaemission lines from the laser beam before they reach thesample.Plasma lines can seriously interfere with Ramanmeasurements.Filtering devices include dispersive monochro-mators and interference filters.5.2 Sampling OpticsCommercial instruments can be pur-chased with sampling optics to focus the laser beam onto asample and to image the Raman scattering onto the monochro-mator entrance slit.Sample chamber adjustments are used tocenter the sample properly and align the Raman scattered light.A schematic view of a conventional 90 Raman scatteringgeometry is shown in Fig.1.The laser beam propagates at aright angle to the direction in which scattered light is collected.It is focused on the sample at the same position as themonochromator entrance slit image.Other geometries such as180backscatteringarealsoused.Withsinglemonochromators,a filter is normally placed in the opticalcollection path to block light at the laser frequency fromentering the monochromator.1This practice is under the jurisdiction of ASTM Committee E13 on MolecularSpectroscopy and Separation Science and is the direct responsibility of Subcom-mittee E13.08 on Raman Spectroscopy.Current edition approved May 1,2014.Published June 2014.Originallyapproved in 1995.Last previous edition approved in 2007 as E1683 02(2007).DOI:10.1520/E1683-02R14E01.2For 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 the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.3 PolarizationFor routine measurements the polariza-tion of the laser at the sample is oriented normal to the planeof the page in Fig.1.However,measurements using differentpolarizations are sometimes used to determine vibrationalsymmetries as part of molecular structure determinations.Avariety of optical configurations can be used to make polariza-tion measurements;a detailed discussion of these is beyond thescope of this practice.Briefly,for polarization simple measure-ments of randomly-oriented samples(most of the clearliqui