4 Spectral Analysis in the NIR Spectroscopy
71
Fig. 4.7 a Time-dependent
NIR spectra changes in the
5200–5060 cm −1 region of a
PHB film during the
melt-crystallization process
at 125 °C. b The
corresponding IR spectra
variations in the
1780–1670 cm −1 region.
Reproduced from Ref. [14]
with permission
and the IR spectrum, but the relative intensity of bands between the free OH bands
and the hydrogen-bonded OH bands is largely changed between them. Accordingly,
special care must be taken in comparison with the relative intensity between a NIR
spectrum and an IR spectrum.
(7) Spectral interpretation by polarization measurement
Polarization measurement, which is popular in IR and Raman spectroscopy, is not
often used in NIR spectroscopy, but it is useful for the determination of the molecularorientation of solid-oriented compounds such as uniaxially stretched polymers. For
more details, see Ref. [14].
(8) Isotope exchange experiments
The use of an isotope shift, which is associated with isotopic substitution, is a traditional method for band assignment in IR and Raman spectroscopy. It is also useful
for NIR spectra analysis, particularly, a deuteration shift. The isotope shift provides
convinced assignment of bands in a number of cases. Force constants can be assumed
71
Fig. 4.7 a Time-dependent
NIR spectra changes in the
5200–5060 cm −1 region of a
PHB film during the
melt-crystallization process
at 125 °C. b The
corresponding IR spectra
variations in the
1780–1670 cm −1 region.
Reproduced from Ref. [14]
with permission
and the IR spectrum, but the relative intensity of bands between the free OH bands
and the hydrogen-bonded OH bands is largely changed between them. Accordingly,
special care must be taken in comparison with the relative intensity between a NIR
spectrum and an IR spectrum.
(7) Spectral interpretation by polarization measurement
Polarization measurement, which is popular in IR and Raman spectroscopy, is not
often used in NIR spectroscopy, but it is useful for the determination of the molecularorientation of solid-oriented compounds such as uniaxially stretched polymers. For
more details, see Ref. [14].
(8) Isotope exchange experiments
The use of an isotope shift, which is associated with isotopic substitution, is a traditional method for band assignment in IR and Raman spectroscopy. It is also useful
for NIR spectra analysis, particularly, a deuteration shift. The isotope shift provides
convinced assignment of bands in a number of cases. Force constants can be assumed