Related Experiment Video
Updated: Jun 27, 2026

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
Resonance Raman measurements of carotenoids using light-emitting diodes
Scott D Bergeson1, Justin B Peatross, N Jay Eyring
1Brigham Young University, Department of Physics Astronomy, Provo, Utah 84602, USA. scott.bergeson@byu.edu
Abstract:
We report on the development of a compact commercial instrument for measuring carotenoids in skin tissue. The instrument uses two light-emitting diodes (LEDs) for dual-wavelength excitation and four photomultiplier tubes for multichannel detection. Bandpass filters are used to select the excitation detection wavelengths. The f1.3 optical system has high optical throughput and single photon sensitivity, both of which are crucial in LED-based Raman measurements. We employ a signal processing technique that compensates for detector drift and error. The sensitivity and reproducibility of the LED Raman instrument compares favorably to laser-based Raman spectrometers. This compact, portable instrument is used for noninvasive measurement of carotenoid molecules in human skin with a repeatability better than 10%.
Related Concept Videos
Raman Spectroscopy: Overview
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and the...
Raman Spectroscopy Instrumentation: Overview
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
Spectroscopy of Carboxylic Acid Derivatives
In the...
UV–Vis Spectroscopy of Conjugated Systems
One of the factors influencing λmax is the extent of conjugation in the...

