Ultraviolet refractometry using field-based light scattering spectroscopy.

Area of Science:

• Biophysics
• Spectroscopy
• Materials Science

Background:

• Accurate refractive index measurement in the deep UV range is crucial for quantifying biomolecules like proteins and DNA.
• Existing methods face challenges in this specific spectral region, limiting applications in biological analysis.

Purpose of the Study:

• To introduce a novel field-based light scattering spectroscopy method for precise refractive index measurements.
• To demonstrate the method's applicability across various wavelengths and sample types, including solutions and microspheres.

Main Methods:

• Utilized quantitative phase microscopy to measure angular scattering distributions of single microspheres (260-315 nm).
• Applied Mie scattering theory with least-squares fitting to determine refractive indices.
• Measured refractive index dispersion for SiO(2) spheres and bovine serum albumin (BSA) solutions.

Main Results:

• Achieved typical accuracy of <=0.003 and precision of <=0.002 for refractive index measurements.
• Successfully extracted specific refractive index increments for BSA solutions.
• Demonstrated the method's effectiveness in the challenging deep UV spectral range.

Conclusions:

• The developed light scattering spectroscopy method provides accurate and precise refractive index measurements in the deep UV.
• This technique is versatile, applicable to diverse samples and wavelengths, advancing biomolecular quantification.
• The method enables detailed characterization of materials and solutions, including specific refractive index increments.