ASTM E573-01(2013)

Standard Practices for Internal Reflection Spectroscopy

SIGNIFICANCE AND USE
4.1 These practices provide general guidelines for the good practice of internal reflection infrared spectroscopy.
SCOPE
1.1 These practices provide general recommendations covering the various techniques commonly used in obtaining internal reflection spectra.2,3 Discussion is limited to the infrared region of the electromagnetic spectrum and includes a summary of fundamental theory, a description of parameters that determine the results obtained, instrumentation most widely used, practical guidelines for sampling and obtaining useful spectra, and interpretation features specific for internal reflection.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

General Information

• Status: Historical
• Publication Date: 31-Dec-2012
• ICS: 71.040.50 - Physicochemical methods of analysis
• Technical Committee: E13 - Molecular Spectroscopy and Separation Science
• Drafting Committee: E13.03 - Infrared and Near Infrared Spectroscopy

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E573 −01 (Reapproved 2013)
Standard Practices for
1
Internal Reflection Spectroscopy
This standard is issued under the fixed designation E573; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Significance and Use
1.1 These practices provide general recommendations cov- 4.1 These practices provide general guidelines for the good
ering the various techniques commonly used in obtaining practice of internal reflection infrared spectroscopy.
2,3
internal reflection spectra. Discussion is limited to the
infrared region of the electromagnetic spectrum and includes a 5. Theory
summary of fundamental theory, a description of parameters
5.1 In his studies of total reflection at the interface between
that determine the results obtained, instrumentation most 6
two media of different refractive indices, Newton (1) discov-
widely used, practical guidelines for sampling and obtaining
ered that light extends into the rarer medium beyond the
useful spectra, and interpretation features specific for internal
reflecting surface (see Fig. 1). In internal reflection
reflection.
spectroscopy, IRS, this phenomenon is applied to obtain
1.2 The values stated in SI units are to be regarded as absorptionspectrabymeasuringtheinteractionofthepenetrat-
standard. No other units of measurement are included in this ingradiationwithanexternalmedium,whichwillbecalledthe
standard. sample (2,3). Theoretical explanation for the interaction
mechanisms for both absorbing and nonabsorbing samples is
2. Referenced Documents
provided by Snell’s law, the Fresnel equations (4), and the
4
Maxwell relationships (5).
2.1 ASTM Standards:
E131Terminology Relating to Molecular Spectroscopy
NOTE 1—To provide a basic understanding of internal reflection
phenomena applied to spectroscopy, a brief description of the theory
E168Practices for General Techniques of Infrared Quanti-
5
appears in Appendix X2. For a detailed theoretical discussion of the
tative Analysis (Withdrawn 2015)
subject, see (4).
E284Terminology of Appearance
6. Parameters of Reflectance Measurements
3. Terminology
6.1 Practical application of IRS depends on many precisely
3.1 Definitions of Terms and Symbols—For definitions of
controlled variables. Since an understanding of these variables
termsandsymbols,refertoTerminologiesE131andE284,and
isnecessaryforproperutilizationofthetechnique,descriptions
to Appendix X1.
of essential parameters are presented.
6.2 Angle of Incidence, θ—When θ is greater than the
1 criticalangle, θ ,totalinternalreflectionoccursattheinterface
c
These practices are under the jurisdiction of ASTM Committee E13 on
between the sample and the internal reflection element, IRE.
Molecular Spectroscopy and Separation Science and are the direct responsibility of
Subcommittee E13.03 on Infrared and Near Infrared Spectroscopy.
When θ is appreciably greater than θ , the reflection spectra
c
Current edition approved Jan. 1, 2013. Published January 2013. Originally
most closely resemble transmission spectra. When θ is less
approved in 1976. Last previous edition approved in 2007 as E573–01 (2007).
than θ , radiation is both refracted and internally reflected,
DOI: 10.1520/E0573-01R13.
c
2
Internal Reflection Spectroscopy, IRS, is the accepted nomenclature for the
generally leading to spectral distortions. θ should be selected
technique described in these practices. Other terms are sometimes used which
far enough away from the average critical angle of the
include: Attenuated Total Reflection, ATR; Frustrated Total Reflection, FTR;
sample—IRE combination that the change of θ through the
Multiple Internal Reflection, MIR; and other less commonly used terms. In older c
literature, one may find references to Frustrated Total Internal Reflection, FTIR. region of changing index (which is related to the presence of
This should not be confused with Fourier Transform Infrared Spectroscopy FT-IR.
the absorption band of the sample) has a minimal effect on the
3
Other terms sometimes used for referring to the internal reflection element are:
shapeoftheinternalreflectionband.Increasingθdecreasesthe
ATR crystal, MIR plate, or sample plate.
4 number of reflections, and reduces penetration. In practice,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
5 6
The last approved version of this historical standard is referenced on Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
www.astm.org
...