PN 350-0453000-02
P a g e
|
7
ATR Probe
The ATR probe may be used to measure solids, liquids, and powders. Intimate contact between the
sample and the ATR crystal is required to obtain a quality spectrum. To use, collect a background
spectrum of a clean ATR crystal. Next, place the ATR tip on the sample and exert pressure to obtain good
contact and collect the sample spectrum.
The ATR probe is sealed up to 60 mm beyond the ATR probe tip. Do not submerge the probe into a
liquid deeper than 60 mm. Double score lines are etched on the probe head to indicate the maximum
immersion allowed. Isopropyl alcohol, a mild solvent, is recommended for cleaning the ATR crystal using
a cotton swab.
Zinc Selenide
Zinc Selenide (ZnSe) is a general-purpose ATR material. It has limited use with strong acids and alkalis.
The acceptable pH range is 5 through 9. Additionally, complexing agents such as ammonia and EDTA will
erode its surface because of the formation of complexes. The maximum temperature range for the ZnSe
probe is ambient to 95 °C.
Germanium
Germanium (Ge) has been used extensively in the past as a higher refractive index material for samples
that have a high re
fractive index such as carbon fi
lled samples. Due to its higher refractive index, spectra
collected with a Ge ATR crystal are weaker in spectral absorbance compared to spectra collected with
ZnSe or diamond/ZnSe composite ATR crystals. The acceptable pH range is from 1 to 14. The maximum
temperature range for the Ge probe is ambient to 95 °C.
Diamond/ZnSe Composite
Diamond is one of the most rugged optical materials. It can be used for the analysis of a wide range of
samples including acids, bases, and oxidizing agents. Diamond is also scratch and abrasion resistant. Its
disadvantage is the intrinsic absorption from approximately 2300 to 1800 cm
-1
. The maximum
temperature range for the diamond/ZnSe probe is ambient to 60 °C.
