ASTM E2529-06e1
(Guide)Standard Guide for Testing the Resolution of a Raman Spectrometer
Standard Guide for Testing the Resolution of a Raman Spectrometer
SIGNIFICANCE AND USE
4.1 Assessment of the spectrometer resolution and instrument line shape (ILS) function of a Raman spectrometer is important for intercomparability of spectra obtained among widely varying spectrometer systems, if spectra are to be transferred among systems, if various sampling accessories are to be used, or if the spectrometer can be operated at more than one laser excitation wavelength.
4.2 Low-pressure discharge lamps (pen lamps such as mercury, argon, or neon) provide a low-cost means to provide both resolution and wave number calibration for a variety of Raman systems over an extended wavelength range.
4.3 There are several disadvantages in the use of emission lines for this purpose, however.
4.3.1 First, it may be difficult to align the lamps properly with the sample position leading to distortion of the line, especially if the entrance slit of the spectrometer is underfilled or not symmetrically illuminated.
4.3.2 Second, many of the emission sources have highly dense spectra that may complicate both resolution and wave number calibration, especially on low-resolution systems.
4.3.3 Third, a significant contributor to line broadening of Raman spectral features may be the excitation laser line width itself, a component that is not assessed when evaluating the spectrometer resolution with pen lamps.
4.3.4 An alternative would use a Raman active compound in place of the emission source. This compound should be chemically inert, stable, and safe and ideally should provide Raman bands that are evenly distributed from 0 cm-1 (Raman shift) to the C-H stretching region 3000 cm -1 and above. These Raman bands should be of varying bandwidth.
4.4 To date, no such ideal sample has been identified; however carbon tetrachloride (see Practice E1683) and naphthalene (see Guide E1840) have been used previously for both resolution and Raman shift calibration.
4.5 The use of calcite to assess the resolution of a Raman system will be addressed in this guid...
SCOPE
1.1 This guide is designed for routine testing and assessment of the spectral resolution of Raman spectrometers using either a low-pressure arc lamp emission lines or a calibrated Raman band of calcite.
1.2 The values given in SI units are to be regarded as the standard.
1.3 Because of the significant dangers associated with the use of lasers, ANSI Z136.1 shall be followed in conjunction with this practice.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: E2529 − 06
StandardGuide for
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Testing the Resolution of a Raman Spectrometer
This standard is issued under the fixed designation E2529; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
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ε NOTE—Added title to Table 1 in August 2013.
1. Scope 4. Significance and Use
1.1 This guide is designed for routine testing and assess-
4.1 Assessment of the spectrometer resolution and instru-
ment of the spectral resolution of Raman spectrometers using
ment line shape (ILS) function of a Raman spectrometer is
either a low-pressure arc lamp emission lines or a calibrated
important for intercomparability of spectra obtained among
Raman band of calcite.
widely varying spectrometer systems, if spectra are to be
transferred among systems, if various sampling accessories are
1.2 The values given in SI units are to be regarded as the
to be used, or if the spectrometer can be operated at more than
standard.
one laser excitation wavelength.
1.3 Because of the significant dangers associated with the
4.2 Low-pressure discharge lamps (pen lamps such as
use of lasers, ANSI Z136.1 shall be followed in conjunction
mercury, argon, or neon) provide a low-cost means to provide
with this practice.
both resolution and wave number calibration for a variety of
1.4 This standard does not purport to address all of the
Raman systems over an extended wavelength range.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.3 There are several disadvantages in the use of emission
priate safety and health practices and determine the applica- lines for this purpose, however.
bility of regulatory limitations prior to use.
4.3.1 First, it may be difficult to align the lamps properly
with the sample position leading to distortion of the line,
2. Referenced Documents
especially if the entrance slit of the spectrometer is underfilled
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or not symmetrically illuminated.
2.1 ASTM Standards:
E131 Terminology Relating to Molecular Spectroscopy 4.3.2 Second, many of the emission sources have highly
dense spectra that may complicate both resolution and wave
E1683 Practice for Testing the Performance of Scanning
Raman Spectrometers number calibration, especially on low-resolution systems.
E1840 Guide for Raman Shift Standards for Spectrometer 4.3.3 Third, a significant contributor to line broadening of
Calibration
Raman spectral features may be the excitation laser line width
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itself, a component that is not assessed when evaluating the
2.2 ANSI Standard:
spectrometer resolution with pen lamps.
ANSI Z136.1 Safe Use of Lasers
4.3.4 AnalternativewoulduseaRamanactivecompoundin
3. Terminology
place of the emission source. This compound should be
chemically inert, stable, and safe and ideally should provide
3.1 Definitions—Terminology used in this guide conforms
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Raman bands that are evenly distributed from 0 cm (Raman
to the definitions in Terminology E131.
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shift) to the C-H stretching region 3000 cm and above.These
Raman bands should be of varying bandwidth.
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This guide is under the jurisdiction of ASTM Committee E13 on Molecular
4.4 To date, no such ideal sample has been identified;
Spectroscopy and Separation Science and is the direct responsibility of Subcom-
however carbon tetrachloride (see Practice E1683) and naph-
mittee E13.08 on Raman Spectroscopy.
thalene (see Guide E1840) have been used previously for both
Current edition approved Dec. 1, 2006. Published December 2006. Originally
approved in 2006. Last previous edition approved in 2006 as E2529– 06. DOI:
resolution and Raman shift calibration.
10.1520/E2529-06E01.
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4.5 The use of calcite to assess the resolution of a Raman
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
system will be addressed in this guide. Calcite is a naturally
Standards volume information, refer to the standard’s Document Summary page on
occurring mineral that possesses many of the desired optical
the ASTM website.
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properties for a Raman resolution standard and is inexpensive,
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. safe, and readily available.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E2529 − 06
FIG. 1 Calcite Raman Spectrum
4.6 The spectral bandwidth of dispersive Raman spectrom- 785-nm excitation. These pen lamps
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