Chirascan CD Spectrometers

By Applied Photophysics

Chirascan CD spectrometers lead the way in providing high-sensitivity CD measurements, making them an invaluable tool for researchers in structural biology, pharmaceutical development, and material science. A Chirascan CD spectrometer generates left- and right-circularly polarised light and measures the differential absorption of these two components by a chiral sample. The system comprises several key components that work together to ensure precise and accurate measurements. - The Light Source: A Xenon Arc Lamp Chirascan systems use a 150W Xenon arc lamp as the light source, which produces high-intensity ultraviolet (UV) and visible light. This ensures a high signal-to-noise ratio, enabling high-quality data. However, exposure of oxygen to UV light can produce ozone, which can degrade optical components. To counteract this, the system features an Active Nitrogen Management System (ANMS) to purge oxygen from the optical pathway. - The Monochromator: Precision Polarisation Selection Unlike conventional dual-prism spectrometers, Chirascan systems not only utilise two prisms, but a dual-polarising monochromator, which offers purer polarised light. - Photoelastic Modulator (PEM): Generating Circularly Polarised Light A crucial step in CD spectroscopy is converting linearly polarised light into circularly polarised light. This is achieved using a Photoelastic Modulator (PEM), which modulates the phase shift between orthogonal components of the light wave. By controlling this modulation, the system alternates between left- and right-circularly polarised light at a high frequency. - The Sample Interaction: Measuring Circular Dichroism Once the circularly polarised light interacts with a chiral sample, the differential absorption of left- and right-handed circularly polarised light is measured. This difference is what generates the characteristic CD spectrum, which provides insights into the secondary and tertiary structure of proteins, protein-ligand interactions, and other molecular properties. - High-Sensitivity Detection Chirascan systems are designed for maximum sensitivity and precision. Chirascan spectrometers stand out due to their advanced optical design and high-performance detection capabilities. Key advantages include: - Enhanced polarisation purity with dual-polarising monochromators - Solid state detection that provides superior sensitivity - Active Nitrogen Management System (ANMS) to prolong optical component lifespan - Modular accessories for expanded functionality, including fluorescence and stopped-flow experiments