FTIR-Spectrometer; Bruker Vertex 70 with a Hyperion 2000 IR-Microscope

Bruker Vertex 70 FTIR spectrometer equipped with a Hyperion 2000 IR microscope.

The Bruker Vertex 70 FTIR spectrometer is a high-quality class FTIR spectrometer for structural and semi-quantitative chemical analyses of inorganic and organic crystalline and amorphous solids, as well as of fluids. The biggest advantage of the FTIR spectroscopy, compared to other analytical methods, is its application field as it covers not only crystalline but also amorphous materials and, it assists to the detection of molecular species in solids, including water, (OH)^-, (CO₃)^2- and several organic molecules. This FTIR spectrometer is a stationary device with an overall weight of ~110 kg and dimensions of 130×65×85 cm (L×D×H). It is equipped with a RT-DLaTGS detector with a 200–12000 cm^-1 spectral range, KBr window and a sensitivity of D* > 2×10⁸ cm Hz^1/2 W^-1 (macrochamber). There are two stages for attenuated total reflectance (ATR) FTIR spectroscopy in a macrochamber for solid samples, powders, and liquids. The coupled IR microscope allows to measure the IR signal in either reflection or transmission regime from spatial areas down to ~30*30 mm. The microscope equipped with a motorised X-Y stage for FTIR mapping as well as with objectives for surface-sensitive ATR and reflection-absorption infrared (RAIR) spectroscopy with a submillimeter spatial resolution. The latter method is particularly suitable to study corrosion layers on metallic writing supports (e.g. patina on coins). The microscope operates an LN₂ cooled MCT detector with a 620–12000 cm^-1 spectral range and a sensitivity of D* > 2×10¹⁰ cm Hz^1/2 W^-1 (microscope). For better performance, the spectrometer should be purged with, nitrogen gas while collecting spectra either in a macrochamber or with a microscope.

General description: Bruker Vertex 70 FT-IR spectrometer equipped with Ge and diamond ATR stages as well as with a Hyperion 2000 IR microscope with Ge-ATR and GI(RAIR) objectives.
Application aim: Structural and semi-quantitative chemical analysis of inorganic and organic crystalline and amorphous solids as well as fluids, can be applied not only to crystalline but also to amorphous materials, detection of molecular species in solids, including water, (OH)^- , (CO₃)^2- organic molecules.
Mobility: stationary
Equipment specifics:
- Power supply with input range of 100-240 V AC, ~2.5 V, 50-60 Hz and output
- range of 24 V DC, 4.75 A and max. 90 W
- Power consumption of 75 W (max. 180 W)
- HeNe laser with a wavelength of 632.8 nm
- Air-cooled MIR source (globar)
- RT-DLaTGS detector with a 200-12000 cm^-1spectral range, KBr window and
- a sensitivity of D* > 2x10⁸ cm Hz 1/2 W^-1 (macrochamber)
- LN 2 cooled MCT detector with a 600-12000 cm^-1 spectral range and a sensitivity of D* > 2x10¹⁰ cm Hz^1/2W^-1 (microscope)
- Spectrometer and sample compartment need to be purged with nitrogen gas (flow rate of 200 L/h) to reduce the content of unwanted atmospheric interferents
- High stability interferometer with ROCKSOLID permanent alignment
- Instrumental spectral resolution: better than 2 cm^-1
- Peak wavenumber accuracy: ~0.005 cm^-1 at 2000 cm
- Aperture settings from 0.25-8 mm (normally 6 mm)
Application requirements: continuous nitrogen gas supply, 18-35 ^oC and relative humidity ≤ 80%
Operating system: Windows 7
Software package: OPUS 7.5 spectroscopy software
Output: mainly as opus format (100-300 KB) or .dpt (ca. 200 KB)
Evaluation program: OriginPro 2019b
Contact: Stelios Aspiotis, aspiotis@uni-hamburg.de(stylianos.aspiotis"AT"uni-hamburg.de)
Location of the equipment: Mineralogisch-Petrographisches Institut, MPI, (Grindelallee 48, Hamburg)

The following experiments can be performed with the Bruker Vertex 70 FTIR spectrometer:

Experiments in macrochamber: KBr pellet technique in transmission

Preparation of KBr pellets according to the KBr technique is a micro-destructive analytical method as only ~ 1 mg of sample is required, compared to the 100 mg needed for the p-XRD analytical method. In this case, the entire volume of the sample is probed. Other device-related limitations and requirements are listed below:

Sample required: yes, only ~ 1 mg, preparation according to the KBr technique
Contact required: yes but much smaller compared with powder XRD
Interaction spot dimensions: the entire volume of the sample is probed
Limitations: specific spectral range, equipment for preparing KBr pellets
Set up time: ~ 30 min (preparation and measurement of KBr pellet)
Average time for measuring: a minimum of 32 scans/measurement is needed (corresponds to ca. 40 sec) for statistical reasons, while as an example we can define the measuring time as ~ 90 sec for 64 scans in the 200-8000 cm^-1 spectral range with an instrumental resolution of 2 cm^-1 (sample was marble powder).
Average time for processing: couple of min/spectrum (depends on the complexity of the sample)

Experiments in macrochamber: Attenuated Total Reflection (ATR)-FTIR

The MPI is in possession of two ATR units, namely of a Bruker Platinum ATR unit A225 equipped with a diamond crystal (refractive index n = 2.43, spectral range: 10-10000 cm^-1) and of a PIKE Technologies MIRacle^TM ATR unit equipped with a Ge single reflection ATR plate (n = 4, spectral range: 780-5500 cm^-1). ATR technique is relative versatile, as it can be applied either to powders and monolithic plate-like samples with a flat surface (2x2 mm²) or directly to the analysed object (not bigger than 120x120 mm and not smaller than 2x2 mm), which makes it in this case a preparation-free, non-invasive and non-destructive analytical method. Other handy instrumental specifications and limitations can be found below:

Equipment specifics:

The Platinum ATR unit is equipped with a diamond crystal (refractive index n = 2.43, spectral range: 10-10000 cm^-1).
The MIRacle TM ATR unit is equipped with a Ge single reflection ATR plate (n = 4, spectral range: 780-5500 cm^-1).

Sample required: requires powder or monolithic plate-like sample with a flat surface

(2x2 mm), analysed object not bigger than 120 x 120 mm and not smaller than 2x2 mm

Contact required: yes
Interaction spot dimensions: 2x2 mm
Limitations: Samples should have a lower refractive index than the one of the ATR crystal, low absorption intensity in the high-wavenumber region, while ATR corrections are necessary and peak positions may deviate from those measured in transmission.
Set up time: ~5 min (purging the macrochamber with N₂),
Average time for measuring: minimum of 32 scans/measurement is needed (corresponds to ~40 sec) for statistical reasons
Average time for processing: a couple of min/spectrum (depends on the complexity of the sample)

Hyperion 2000 IR-microscope equipped with a 15x IR objective, 20x ATR objective and a 15x GIR objective

FTIR spectroscopy equipped with the Hyperion 2000 IR microscope operates in reflectance, and it is a totally preparation-free, contactless and non-destructive analytical technique as the sample can be placed intact under the microscope. Some instrumental limitations do not allow measurements in the spectral range below 650 cm^-1 and the interpretation of the acquired data is relatively complicated when the sample surface is rough. Additional device-related specifications and limitations can be found below:

Operating conditions: 18-30^oC and relative humidity ≤ 70%
Equipment specifics:

Sample visualisation is achieved through a Hitachi CCD camera (model: KP-D20BP) and LCD monitor.
ATR Ge crystal tip diameter is ~ 100 μm
For the ATR objective: contact pressure with 5 different pressure levels (0.5-8 Newton) which can leave an ATR imprint with diameter of 100 μm on the surface of the analysed material
2D mapping via a Märzhäuser Wetzlar motorized XYZ-stage, joystick-controlled with travel range in x- and y-direction: 5.0 x 7.5 cm

Sample required: no, analysed object not thicker than ~20, 40 and 2 mm for IR, ATR and GIR objective, respectively
Contact required: no/yes, no for IR, yes for ATR and GIR objective
Interaction spot dimensions: ~30, 100 and 20 μm with the IR, ATR and GIR objective, respectively
Set up time: ~30 min (filling with LN₂, calibration with Au-coated plane mirror)
Average time for measuring: minimum of 32 scans/measurement is needed (corresponds to ~40 sec) for statistical reasons, for instance, a total of ~90 sec for 64 scans in the 600-6000 cm^-1 spectral range (measurement in reflection on marble) is required.
Average time for processing: a couple of min/spectrum (depends on the complexity of the sample)