IRT
Attenuated Total Reflectance (ATR) accessories have significantly reduced the amount of sample preparation required for macro FTIR measurements. Before ATR was developed, samples could only be measured in either transmission or reflection mode, which involves time consuming dilution, pellet making, or diffuse reflectance measurement. FTIR microscopy has the same sample preparation as macro FTIR measurements, which can be significantly reduced by using an ATR objective.
ClearView™ ATR Objectives
ClearView™ ATR objectives allow both observation of the sample and ATR spectral measurement using a single objective, by switching the crystal position between Survey mode (up) and ATR mode (down). ClearView™ ATR objectives consist of a Cassegrain and an ATR crystal made from germanium, zinc selenide or diamond, which are transparent to visible and infrared light, enabling simultaneous measurement and observation when the sample before and when in contact with the crystal (germanium is used only for survey mode and cannot be used for sample contact).
The measurement area is first observed and selected using the ATR–5000–S type objectives, and then after the crystal has made contact (not possible with conventional ATR objectives), the correct selection of the contact area is confirmed.
ATR Mapping
In transmission or reflection mapping, the Cassegrain objective never comes into direct contact with the sample, so the stage can easily be moved to map an area; however, in ATR mapping, the ATR objective must be in direct contact with the sample. When performing traditional ATR mapping measurements, the ATR objective is lowered onto the sample to acquire a single measurement point, then the ATR objective is raised to allow the sample stage to move to the next measurement point, before lowering the ATR objective back onto the sample.
IQ Mapping™
When performing IQ Mapping™ measurements, the ATR objective remains in contact with the sample for the entire mapping measurement. Each measurement point is acquired by moving the aperture around the field of view of the objective (yellow square in red grid).
IQ Mapping™ eliminates cross-contamination, saves time during sample measurement, and minimizes the risk of the sample moving or being damaged when the point of contact for measurements is changed. While IQ Mapping™ is particularly useful when performing ATR measurements, it offers similar benefits in transmission and reflection measurement modes.
ATR-5000-SS
(Zinc Sulfide)
RI (1,000 cm-1): 2.2
Magnification (Survey): 16x
Numerical Aperture (NA): 0.76
Wavenumber Range:
7,000 – 700 cm-1
Measurement Area:
180 µm x 180 µm
ATR-5000-SD
(Diamond)
RI (1,000 cm-1): 2.4
Magnification (Survey): 16x
Numerical Aperture (NA): 0.70
Wavenumber Range:
7,000 – 700 cm-1
Measurement Area:
180 µm x 180 µm
ATR-5000-SG
(Germanium)
RI (1,000 cm-1): 4
Magnification (Survey): 16x
Numerical Aperture (NA): 0.76
Wavenumber Range:
5,200 – 650 cm-1
Measurement Area:
100 µm x 100 µm
ATR-5000-MG
(Germanium)
RI (1,000 cm-1): 4
Wavenumber Range:
5,000 – 650 cm-1
Measurement Area:
400 µm x 400 µm
Resolution: 12.5 µm
ATR-5000-WG
(Germanium)
RI (1,000 cm-1): 4
Wavenumber Range:
5,000 – 650 cm-1
Measurement Area:
1,600 µm x 1,600 µm
Resolution: 50 µm
