Related Experiment Video
Updated: Jan 14, 2026
07:38
Characterization of Biological Absorption Spectra Spanning the Visible to the Short-Wave Infrared
Published on: January 10, 2025
2.9K
Improving Bandgap Determination by Optical Spectroscopy: Comparative Evaluation of ISARS, UV-vis, and Diffuse
Huy Pham1, Juliana Cardoso Neves2, Rongjing Yan1
1Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States.
ACS Measurement Science Au
|October 20, 2025
Summary
Integrating sphere-assisted resonance synchronous spectroscopy (ISARS) offers a reliable method for determining optical bandgaps by accurately measuring absorption coefficients. This technique outperforms UV-vis and diffuse reflectance spectroscopy, especially for diverse materials.
Area of Science:
- Materials Science
- Spectroscopy
- Optoelectronics
Background:
- Accurate optical bandgap determination is crucial for photoactive materials.
- The Tauc plot method relies on precise absorption coefficient (α) quantification.
- Existing spectroscopic methods have limitations in accuracy and applicability.
Purpose of the Study:
- To systematically evaluate and compare UV-vis, DRS, and ISARS for absorption coefficient measurement.
- To assess the suitability of these techniques for Tauc plot-based bandgap analysis.
- To identify the most robust and versatile method for bandgap characterization.
Main Methods:
- Development of generalized mathematical models for UV-vis, DRS, and ISARS spectral signal parametrization.
- Evaluation of each technique's ability to approximate the true absorption coefficient spectrum.
- Comparison of performance based on sample type (solid/solution), scattering, and fluorescence interference.
Main Results:
- UV-vis spectroscopy is highly limited, suitable only for non-interfering samples.
- DRS and ISARS show comparable accuracy for solids but DRS is sensitive to fluorescence and limited to solids.
- ISARS demonstrates superior performance: effective for solids and solutions, resilient to interference, and requires minimal preparation.
Conclusions:
- ISARS is a highly accurate, broadly applicable, and user-friendly technique for bandgap characterization.
- Its robustness against scattering and fluorescence makes it ideal for diverse materials.
- ISARS, implementable with standard equipment, promises to accelerate photoactive material discovery.
Related Concept Videos
01:14UV–Vis Spectrometers
3.4K
The absorbance of UV and visible (UV–visible) radiations is measured using a UV–visible spectrophotometer. Deuterium lamps, which emit UV radiation, and tungsten lamps, which produce radiation in the visible region, are used as light sources in UV–visible spectrophotometers. A monochromator or prism is used for diffraction grating, i.e., to split the incoming radiation into different wavelengths. A system of slits is used to focus the desired wavelength on the sample cell.
3.4K
01:02Ultraviolet and Visible (UV–Vis) Spectroscopy: Overview
4.4K
Ultraviolet–visible (UV–visible or UV–Vis) spectroscopy is an analytical technique that investigates the interaction between matter and UV–Vis light within the electromagnetic spectrum. This method is widely used for its versatility, simplicity, and relatively quick data acquisition, making it valuable for both qualitative and quantitative analysis. When UV–Vis radiation passes through a material, molecules absorb light depending on the energy required for...
4.4K
01:16UV–Vis Spectroscopy: Molecular Electronic Transitions
2.7K
In Ultraviolet–Visible (UV–Vis) spectroscopy, the absorption of electromagnetic radiation is used to probe the electronic structure of molecules. This technique provides insights into molecular electronic transitions, particularly the movement of electrons between different molecular orbitals. Radiation is absorbed if the energy of the electromagnetic radiation passing through the molecule is precisely equal to the energy difference between the excited and ground states. During this...
2.7K
01:09UV–Vis Spectroscopy: Beer–Lambert Law
6.6K
The Beer-Lambert law describes the relationship between absorbance and concentration, which combines the principles established by scientists Johann Heinrich Lambert and August Beer. Lambert's law states that when light passes through a medium, the loss in intensity is directly proportional to the original intensity and the path length of the light. Beer's law proposed that the transmittance of a solution remains constant if the product of concentration and path length is constant. The modern...
6.6K
01:29UV–Vis Spectroscopy: Woodward–Fieser Rules
28.1K
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...
28.1K
01:30UV–Vis Spectrum
2.0K
When light passes through a substance, a portion of the light is absorbed while the remaining light is reflected or transmitted. If the molecule absorbs light between the wavelengths of 180–400 nm range, the UV spectrum is obtained, and if it absorbs light in the 400–780 nm wavelength range, the visible spectrum is obtained.
The UV–Vis spectrum of a molecule is the plot of its absorbance versus wavelength. The plot is drawn by taking molar...
The UV–Vis spectrum of a molecule is the plot of its absorbance versus wavelength. The plot is drawn by taking molar...
2.0K