(c) Determine the peak position as the midpoint of the horizontal line that intersects at 80% of the peak height, and
save the result.
(d) Steps (a) through (c) need to be applied to all the spectra
that have been recorded during the run.
2. In a spreadsheet program, enter column listing: (1) spectrum
number, (2) time point of collection and/or sample temperature during collection, and (3) position of the OH band
(νOH). Create a plot in which νOH is plotted as a function of
the sample temperature. The glass transition temperature can
be determined as the intersection of linear regression lines in
the glassy and liquid state.
4 Notes
1. A TGS (triglycine sulfate) detector can also be used. The signalto-noise ratio for such a detector is not as good compared to
that of an MCT (mercury cadmium telluride) detector, which
increases the data acquisition time to obtain spectra of sufficient quality for data analysis.
2. An air compressor is needed to run the FTIR purge gas generator. If no air compressor system is available, the generator can
also be hooked up to a nitrogen gas cylinder.
3. Procedures and methods can easily be adapted using FTIR
systems from other suppliers (e.g., Thermo Scientific, Bru ¨ker).
Furthermore, Labview and MATLAB software can also be used
for data acquisition and spectra analysis.
4. Commercially available temperature-controlled sample holders
like the one from Harrick can be replaced by custom-designed
devices, allowing more flexibility in sample handling and temperature regimes.
5. A liquid nitrogen cryogenic pump micro-dosing system from
Norhof (Maarssen, Netherlands) can also be used for cooling
the sample holder.
6. With newer setups, FTIR purging is not needed, but nevertheless it may still be used to improve spectral quality. For
low-temperature studies, however, a purge system is needed
to purge the sample area of the FTIR setup.
7. Fringing is visible as a sinusoid shape interfering throughout
the spectra. If fringing is observed, mount the windows again
in the sample holder or use another pair of windows to acquire
a new background spectrum.
In situ Infrared Spectroscopy
347
save the result.
(d) Steps (a) through (c) need to be applied to all the spectra
that have been recorded during the run.
2. In a spreadsheet program, enter column listing: (1) spectrum
number, (2) time point of collection and/or sample temperature during collection, and (3) position of the OH band
(νOH). Create a plot in which νOH is plotted as a function of
the sample temperature. The glass transition temperature can
be determined as the intersection of linear regression lines in
the glassy and liquid state.
4 Notes
1. A TGS (triglycine sulfate) detector can also be used. The signalto-noise ratio for such a detector is not as good compared to
that of an MCT (mercury cadmium telluride) detector, which
increases the data acquisition time to obtain spectra of sufficient quality for data analysis.
2. An air compressor is needed to run the FTIR purge gas generator. If no air compressor system is available, the generator can
also be hooked up to a nitrogen gas cylinder.
3. Procedures and methods can easily be adapted using FTIR
systems from other suppliers (e.g., Thermo Scientific, Bru ¨ker).
Furthermore, Labview and MATLAB software can also be used
for data acquisition and spectra analysis.
4. Commercially available temperature-controlled sample holders
like the one from Harrick can be replaced by custom-designed
devices, allowing more flexibility in sample handling and temperature regimes.
5. A liquid nitrogen cryogenic pump micro-dosing system from
Norhof (Maarssen, Netherlands) can also be used for cooling
the sample holder.
6. With newer setups, FTIR purging is not needed, but nevertheless it may still be used to improve spectral quality. For
low-temperature studies, however, a purge system is needed
to purge the sample area of the FTIR setup.
7. Fringing is visible as a sinusoid shape interfering throughout
the spectra. If fringing is observed, mount the windows again
in the sample holder or use another pair of windows to acquire
a new background spectrum.
In situ Infrared Spectroscopy
347