Related Experiment Video
Updated: Jun 17, 2026
10:12
Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples
Published on: June 19, 2018
FTIR spectral components of schwertmannite.
Jean-François Boily1, Paul L Gassman, Tetyana Peretyazhko
1Department of Chemistry, Umea University, Umea SE-901 87, Sweden. jean-francois.boily@chem.umu.se
Environmental Science & Technology
|January 14, 2010
Summary
This study identifies key sulfate species in synthetic schwertmannite using Fourier transform infrared (FTIR) spectroscopy. The findings help in recognizing sulfate groups in natural schwertmannite samples.
Area of Science:
- Mineralogy
- Geochemistry
- Spectroscopy
Background:
- Schwertmannite is a sulfate mineral found in acidic environments.
- Understanding sulfate speciation in schwertmannite is crucial for environmental and geochemical studies.
- Fourier transform infrared (FTIR) spectroscopy is a powerful tool for mineral analysis.
Purpose of the Study:
- To identify and characterize dominant sulfate species within synthetic schwertmannite.
- To develop a spectral library for analyzing sulfate groups in natural schwertmannite.
- To elucidate the bonding mechanisms of sulfate ions in the schwertmannite structure.
Main Methods:
- Synthesis of schwertmannite under varying aqueous conditions (pH 3-9).
- Acquisition of FTIR spectra from N(2)(g)-dry samples.
- Application of multivariate curve resolution (MCR) analysis to extract spectral components.
- Heating experiments up to 130°C to validate spectral assignments.
Main Results:
- Three dominant FTIR spectral components corresponding to different sulfate species were extracted.
- Component I was assigned to both hydrogen- and iron-bonded sulfate ions.
- Components II and III were tentatively assigned to protonated sulfate species, with Component II confirmed by heating experiments.
Conclusions:
- The extracted spectral components provide a basis for identifying sulfate species in natural schwertmannite.
- This research enhances the understanding of sulfate incorporation and bonding in schwertmannite.
- The study offers a valuable tool for geochemical and environmental monitoring involving schwertmannite.
Related Concept Videos
01:25IR Spectrometers
There are two main infrared (IR) spectrophotometers: dispersive IR spectrometers and Fourier transform infrared (FTIR) spectrometers. In a dispersive IR spectrometer, a beam of infrared radiation produced by a hot wire is divided into two parallel equal-intensity beams using mirrors. One beam passes through the sample, while another is a reference beam. The beams then move through the monochromator, which separates the radiations into a continuous spectrum of different frequencies. The...
01:24IR Spectroscopy: Molecular Vibration Overview
When Infrared (IR) radiation passes through a covalently bonded molecule, the bonds transition from lower to higher vibrational levels. The fundamental vibrational motions that result in infrared absorption can be classified as stretching or bending vibrations.
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
01:20Raman Spectroscopy: Overview
The underlying principle of Raman spectroscopy is based on the interaction between light and matter, specifically molecules' inelastic scattering of photons. When a monochromatic beam of light, typically from a laser source, interacts with a sample, most scattered light has the same frequency as the incident light. This is known as Rayleigh scattering.
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and the...
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and the...
01:03IR Frequency Region: Fingerprint Region
IR spectra are divided into two main regions: the diagnostic region and the fingerprint region. The diagnostic region of the spectrum lies above 1500 cm−1. The absorptions resulting from single-bond vibrations of the N–H, C–H, and O–H stretch at higher wavenumbers and appear on the left side of the spectrum. The stretching absorptions of the C≡C and C≡N occur between 2100–2300 cm−1. In contrast, those arising from stretching absorptions of the C=O, C=N, and C=C occur between 1600–1850 cm−1.
The...
The...
01:24IR Frequency Region: X–H Stretching
In IR spectroscopy, signals produced by the X−H bonds (such as C−H, O−H, or N−H) can be observed in the frequency range of 2700–4000 cm–1. The C−H stretching vibration forms sharp bands in the region 2850–3000 cm–1. The presence of the O−H stretching vibration leads to the forming of an absorption band in the frequency range 3650–3200 cm−1. At the same time, N−H stretching can be confirmed by absorption bands in the 3500–3100 cm−1 range. Even though both O−H and N−H bonds vibrate at a similar...
01:29UV–Vis Spectroscopy: Woodward–Fieser Rules
UV–Visible absorption spectra of conjugated dienes arise from the lowest energy π → π* transitions. The light-absorbing part of the molecule is called the chromophore, and the substituents directly attached to the chromophore are called auxochromes. A strong correlation exists between the absorption maxima, λmax, and the structure of a conjugated π system. The Woodward–Fieser rules predict the value of λmax for a given structure by adding the contributions...