UV-Vis-NIR Spectroscopy

Ultraviolet-Visible-Infrared (UV-Vis-NIR) spectroscopy measures the absorption, reflection, and transmission spectrum of a material. It is used to characterize material properties such as optical density in polycarbonate lenses, molar extinction coefficient in metal-ligand compounds, and bandgap energy in quantum dots.

Ebatco’s Agilent Cary 7000 Universal Measurement Spectrophotometer (UMS) combined with a Diffuse Reflectance Accessory (DRA) is state-of-the-art when it comes to complete optical sample characterization. The base instrument is a double-beam spectrophotometer which accounts for light source intensity fluctuations and has a wavelength range of 175-3300 nm. In addition, the base instrument is capable of measuring up to an optical density of 10 Abs, meaning it can measure one part in 10 billion of transmitted light through a sample.

The Universal Measurement Accessory (UMA) allows for independent control of the sample angle and detection angle. The sample can be rotated a full 360° and the detector can be rotated around the sample from 10-350°. In addition, the input polarization can be tuned to S- or P-polarization, and any polarization in between. The UMA can achieve absolute reflectance, absolute transmittance, and absolute absorptance values at nearly any angle without having to touch the sample or beam routing optics.

Finally, the DRA is equipped with a 150-mm integrating sphere that is used for measuring the diffuse reflectance, diffuse transmittance, and diffuse transflectance of a sample.

The Cary 7000 UMS with DRA can be used in a wide range of industries including:

• Colorimetry
• Glasses
• Optics Manufacturing QA/QC
• Nanomaterials
• Photonics
• Polymers & Plastics
• Pharmaceuticals
• Roofing Materials
• Semiconductors
• Solar Cell Materials
• Visual Displays

Typical Experimental Results

Below are demonstrations of different instrument modalities that are uniquely configured to measure specific material properties:

Concentration Determination Using Absorbance Calibration Curve

Absorbance spectra can be used to determine the chemical concentration of a molecule in solution. The absorbance at a particular wavelength of standards with various concentrations are used to build a calibration curve. The concentration of the chromophore in an unknown solution can then be determined.

Absorbance spectrum (left) and calibration curve (right).

Polarization- and Angle-Resolved Reflectance

The specular reflection of a material is useful to know in industries such as optics manufacturing QA/QC and visual displays. Using the UMA, the polarization- and angle-resolved reflectance of a material can be determined. After initial sample loading into the UMA, robotics and automation take care of the rest.

Reflectance data taken by the Cary 7000 UMA (blue) and by the optics manufacturer (red).

Angle-Resolved %R and %T of a Dielectric Filter

The UMA is capable of measuring %R and %T for a single Angle of Incidence (AOI) without having to touch the sample. Below the broadband reflectance and transmittance spectra of a dielectric filter are shown.

Reflectance (red) and transmittance (blue) spectra.

Diffuse Transmittance Using DRA

The inside of the integrating sphere of the DRA is completely covered with a high-reflectance PTFE coating that allows it to collect diffusely scattered light in reflection, transmission, and transflection geometries. The inclusion of a beam trap port allows for the specularly reflected or transmitted light to be included in the measurement, where material properties such as percent haze can be calculated.

Percent haze across the visible spectrum for five common plastics compared to glass.

Instrument: Agilent Cary 7000 Universal Measurement Spectrophotometer

Instrument Key Specifications

Cary 7000 Base Spectrophotometer

UMA

DRA

For more information, please read our application notes:
All application notes can be found here

ASTM Standards

ISO Standards