Related Experiment Video
Updated: Jun 16, 2026

CD Spectroscopy to Study DNA-Protein Interactions
Published on: February 10, 2022
Infrared circular dichroism and linear dichroism spectrophotometer
Abstract:
An instrument for the measurement of circular dichroism (CD) between 5000 cm(-1) and 750 cm(-1) is described. This instrument also can perform high precision linear dichroism measurements in the same wavelength range. A germanium photoelastic modulator having a large linear and angular aperture is used to vary the polarization of monochromatic ir light between left- and right-circularly polarized at 8 kHz. This polarization-modulated light traverses the sample and falls onto a cooled InSb or HgCdTe detector. Phase-sensitive demodulation yields the CD of the sample to a precision of 4 x 10(-6) o.d. units near 3000 cm(-1). The instrument has been used to study ir circular dichroism arising from molecular vibrations in cholesteric liquid crystals, crystals, and fluids. CD arising from low-lying electronic transitions of metal complexes and linear dichroism of polymer films have also been studied.
Related Concept Videos
IR Spectrometers
Infrared (IR) Spectroscopy: Overview
Different compounds display unique properties due to their...
UV–Vis Spectrometers
Spectrophotometry: Introduction
The essential components of a spectrophotometer include a source of electromagnetic radiation, a slot for placing a material to be analyzed, and a...
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...
Applications of IR Spectroscopy: Overview

