FTIR accessories: reflection units

ATR spectroscopy

Reflection methods, above all ATR spectroscopy, have gained increasingly in importance in conjunction with FTIR technology. They are used for samples with poor or no IR transparency, which cannot be analysed in transmission.

One of the major advantages of ATR spectroscopy lies in that sample preparation becomes easier, and the need for complex sample preparation is often avoided completely. High mechanical stability and outstanding chemical resistance have made diamond ATR a highly versatile method for routine analysis of solid and liquid samples in many laboratories.

We offer a full range of single reflection & multi reflection ATR accessories.

Specular reflection

Specular reflection technology analyses the radiation reflected from a surface. The amount of reflected light is dependent on the angle of incidence, refractive index, surface roughness and absorption properties of the sample. Typical applications are the analysis of surface coatings, e.g. surface-treated metals, paint, varnishes and polymers.

The 30° reflection unit is ideal for routine analysis. The monolayer reflection unit enables the angle of incidence to be varied continuously within a range of 8° to 85° (grazing incidence).

Diffuse reflection

Rough surfaces or powder will respond to irradiation with light by predominantly diffuse reflection, with a certain degree of specular reflection. Accessories for measurement of diffuse reflection are therefore designed to optimally collect the diffuse portion whilst minimising the specular portion.

The Selector diffuse reflection unit enables solid samples to be analysed without the need for extensive sample preparation. The optional pressure and temperature sample chamber allows analysis in a controlled atmosphere from room temperature up to 800 °C.

The Minidiff Plus pre-aligned diffuse reflection unit is a low-cost alternative to the Selector diffuse reflection unit.

The pre-adjusted Specac Minidiff Plus Diffuse Reflectance Accessory is a low-cost alternative to the Selector diffuse reflectance accessory. The elimination of the need for adjustment, along with straight-forward, fast sample replacement, make this unit ideally suited to routine analysis. The scope of supply includes the optical unit with base plate, sample cups including holder for powder analysis as well as sample holders with diamond abrasive pads.


The environmental chamber optionally enables the analysis of diffuse reflectance samples in a controlled atmosphere from room temperature to 800 °C. The available pressure range is from vacuum (10-3 Torr) to 33 bar.


The Selector diffuse reflectance accessory enables solid samples to be analysed without the need for extensive sample preparation. The optimised off-axis configuration of the selector optics reduces unwanted directional reflection to a minimum. Selector almost exclusively collects diffuse reflection, which is particularly relevant for quantitative analysis. A special 45° tilted sample holder enables total reflection of a sample to be analysed.


The high number of reflections makes this ATR unit ideal for the analysis of samples with low-intensity bands. The capability of setting the angle of incidence within a range of 30° to 60° enables a variation of the depth of penetration of the IR radiation into the sample and allows recording of depth profiles.


The Gateway ATR system comprises an optical basic unit and a broad range of sample holders for the analysis of liquids, pastes, gels, solid samples, powders, films, etc. The different samples are held in place on the optical basic unit by means of two pins, and are therefore easily removed for exchanging the sample or for replacement. The optical basic unit is fully enclosed so that the transfer optics can be purged with gas.


Quest is a single reflection ATR unit from Specac for spectroscopy in the mid and far infrared spectral regions.


The Golden Gate Diamond ATR unit continues to set new standards in ATR Technology. Due to its hardness and chemical resistance, the solid Type IIa diamond, metal-bonded into a tungsten carbide mount, enables the analysis of a board spectrum of samples, from hard solids to corrosive liquids.

A robust pressure device with sapphire anvil and integral torque mechanisms ensures exceptionally high, repeatable pressure and provides superior optical contact between sample and diamond. This ensures high sensitivity and repeatability of measurements.


This unit is suitable for routine analysis of thin coatings on reflective surfaces. Horizontal sample arrangement significantly facilitates handling. The unit has a free aperture of 20,8 mm. Additional sample masks supplied, having diameters of 5 mm and 10 mm, enable the analysis of small samples as well as the identification of surface defects and inclusions. A reference mirror is also supplied.


This reflectance unit allows the analysis of insoluble monolayer films at an air/liquid interface as well as measurements on thin film coatings on a reflective surface. The angle of incidence can be varied from 8° to 85° (grazing incidence).


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