Spectrometer: FTIR - standard
- Visible, near-, mid-, and far-infrared capabilities
- 0.1 cm-1 resolution
- Include Raman vibrational analysis capabilities
Two Bruker Fourier Transform Infrared (FTIR) spectrometers (IFS66 and IFS66/V) with visible, near-, mid- and far-infrared (IR) capabilities are available at EMSL. With these unique resources, infrared or Raman spectrum of a host of different species—including the most challenging of samples—can be obtained. Examples of work using these FTIRs include:
- Determining the structure and dynamics of interlayer water and chloride ions in hydrotalcite (Wang et al. 2003)
- Determining water content in oil samples (Foster et al. 2001)
- Speciating vegetative bacteria (Thompson et al. 2003)
- Determining structure/function of humic acids (Diallo et al. 2003)
- Determining the structure of vitrified waste and glasses
- Analyzing clays and minerals reacting with simulated tank waste
- Determining transmission characteristics of optical switches.
System Configuration and Operational Overview
The modular design of the Bruker FTIR spectrometers enables rapid changing of detector and beamsplitter combinations, so the researcher may readily change from visible to the near- or mid-IR.
|Vis (400 to 770nm)||silicon||quartz or quartz-CaF2|
|Near-IR 12,900 to 4000cm-1 (770 to 2.5μm)||Ge or InSb or MCT||quartz or quartz-CaF2|
|Mid-IR 4000 to 400cm-1 (2.5 to 25μm)||mercury cadmium telluride (MCT) or DTGS||Potassium bromide|
|Far-IR 400 to 10cm-1 (25 to 1000μm)||helium bolometer or DLATGS||mylar|
All work with the spectrometers and in EMSL laboratories must be performed in compliance with EMSL practices and permits.
This research-grade spectrometer is capable of measurements in the visible, near-IR, and mid-IR with 0.1 cm-1 spectral resolution. It is equipped with a microscope with an approximate resolution of 60 μm, an MCT detector, a visible charge-coupled diode camera, and a 35-mm camera for image capture. The microscope stage has manual and motor drive capabilities for sample mapping. An optional cryogenic cold-stage for sample cooling is available. A host of sampling accessories are available and described below.
The 0.1 cm-1 resolution IFS66/V spectrometer uses all of the same combinations of beamsplitters and detectors as the IFS66. However, the IFS66/V spectrometer is a vacuum bench, which is of great advantage for gas-phase work, for work in the far-IR, or for species whose absorption features lie near those of CO2 or H2O. The instrument interferometer and sample compartments can be evacuated differentially by use of automated shutters with IR transparent windows. A helium bolometer provides greatly enhanced sensitivity in the far-IR. The IFS66/V has step-scan (time-resolved) capability.
Raman Module and Raman Microscope
The infrared spectroscopic capabilities available at EMSL were recently upgraded to include Raman vibrational analyses by addition of an FT-Raman module and Raman microscope to the IFS66/V. The information provided by Raman spectroscopy complements that obtained by infrared spectroscopy, thus allowing complete characterization of molecular vibrations of solids and liquids.
The Bruker FRA 106 Raman module enables complementary measurement of vibrational spectra to those obtained by infrared spectrophotometry. Many vibrational modes of molecules are disallowed in the IR, but are then usually Raman active. It is the complementary nature of these vibrational methods that makes having both analytical techniques so valuable, allowing complete characterization of molecular vibrations of solids and liquids. Raman spectroscopy is also transparent to both water and glass, a real advantage as compared to IR work, especially for aqueous solutions.
The Bruker R 590-D Raman microscope connects directly to the existing FTIR and Raman module, enabling perfect interfacing of the existing 1.5-W, 1064-nm YAG laser to the input optics of the microscope. Raman vibrational spectra can be collected with 20-mm spatial resolution from samples where more than one scattering species are found in close proximity. Use of the dedicated 1064-nm YAG laser for excitation essentially eliminates fluorescence interferences, a real advantage over dispersive Raman methods.
A variety of cells are available for gas, liquid, solid, and slurry samples:
- Attenuated Total Reflectance
- Circle Cell (with zinc selenium or crystal rod)
- Good for strongly absorbing or aqueous-based liquids
- Flow-though capability
- Horizontal/Flat Well Plate (with zinc selenium crystal)
- Good for liquid, semi-liquid and slurry samples.
- Diffuse Reflectance
- Good for soft and hard powdered solids.
- No or simplified sample preparation.
- Specular Reflectance
- Provides a nondestructive method for measuring surface coatings and thin films on reflective substrates without sample preparation (e.g., surface-treated metals, resin, and polymer coatings; painted surfaces; semiconductors etc.).
- Gas Sampling
- Good for gas phase samples and experiments.
- Liquid Transmission
- Various cells are available with a variety of windows and path lengths.
- Flow-though capability.
- Solid Transmission
- Good for potassium bromine pellets; pellet maker available.
- Photoacoustic Cell and Detector
- Handles all samples with little or no sample prep (no thinning or dilution).
- Used to perform absorbance, diffuse reflectance, and transmittance measurements.
- Has controllable sampling depth capability (5 to 100 μm) for layered samples.
- Photoacoustic signal is generated when IR radiation absorbed by the sample converts into heat within the samples.
- This heat diffuses to the sample surface and into an adjacent gas atmosphere.
Researchers who are external to EMSL may use the FTIRs for their research.
All Related Publications Related Publications
- Forsterite [Mg2SiO4)] Carbonation in Wet Supercritical CO2: An in situ High Pressure X-Ray Diffraction Study.
- The surface structure of α-uranophane and its interaction with Eu(III) – An integrated computational and fluorescence spectroscopy study.
- In situ DRIFTS-MS studies on the oxidation of adsorbed NH3 by NOx over a Cu-SSZ-13 zeolite.
- Tomography and High-Resolution Electron Microscopy Study of Surfaces and Porosity in a Plate-Like γ-Al2O3.
- Mechanistic Studies of Methanol Synthesis over Cu from CO/CO2/H2/H2O Mixtures: the Source of C in Methanol and the Role of Water.
All Related Research Highlights Related Research Highlights
- Novel method yields highly reactive, highly hydroxylated TiO2 surface (Water, Sun, Energy)
- New catalyst suggests additional uses for bio-ethanol (Ethanol Evolves)
- New finding shows a research area to expand in EMSL Radiochemistry Annex (Promising Science for Plutonium Cleanup )
- New method to make sodium ion-based battery cells has potential large-scale use (The Heat is On for Rechargeable Batteries)
- Atomic force microscope enables in situ imaging of mineral-fluid interfaces in supercritical carbon dioxide (New Views of High-pressure Meetings)