紫外/可见/近红外光谱（UV / VIS / NIR）

UV/VIS/NIR Spectroscopy

UV/VIS/NIR spectroscopy is a powerful analytical technique used to determine the optical properties (transmittance, reflectance, and absorbance) of both liquids and solids. This method is widely applied for characterizing semiconductor materials, coatings, glasses, and various other research and industrial materials. UV/VIS/NIR spectroscopy operates within the optical wavelength range of 175 nm to 3300 nm.

UV/VIS/NIR Analysis of Solid Samples

UV/VIS/NIR spectroscopy is commonly employed to determine analyte concentrations or the chemical conversion rates of components in solution. This technique measures light absorption within the desired optical range. The sample is dispensed into a cuvette and placed in the optical path between the light source and detector. According to the Beer-Lambert law, at a constant path length and with known absorption coefficients (which are wavelength-dependent), the concentration of the compound in question can be determined based on the amount of light absorbed at that specific wavelength.

UV/VIS/NIR Analysis of Solid Samples

Measuring the Transmittance of Solid Samples:

The sample is placed in front of an integrating sphere. Light from the optical source passes through the sample and enters the integrating sphere. The light is then reflected by the inner surface of the sphere and reaches the detector. Both total transmittance and direct transmittance can be measured. Based on these two parameters, the diffuse transmittance can be derived using the following equation:

T.diffuse = T.total - T.direct

Measurement of Solid Sample Reflectance:

Similar to transmittance measurements, an integrating sphere is required to determine the total reflectance of solid materials. The sample is placed at the rear opening of the integrating sphere. Light from the optical source is reflected by the sample, then subsequently reflected by the inner surface of the integrating sphere before reaching the detector. In addition to total reflectance, diffuse reflectance can also be measured. Specular reflectance can be calculated from the total and diffuse reflectance data using the following equation:

Rspecular = R.total -Rdiffuse

Calculation of Absorbance for Solid Samples:

The percentage absorbance is defined as the percentage of incident light beam absorbed by the sample, representing the portion that is neither reflected nor transmitted. Absorbance can be calculated from reflectance and transmittance measurements using the following relationship:

％A = 100％–％Rtotal –％Ttotal

Optimal Applications of UV/VIS/NIR Spectroscopy

• Characterizes the optical behavior of liquids and solids within the 175 nm to 3300 nm wavelength range

• Precisely measures analyte concentrations in solutions

• Determines both iron content (Fe) and oxidation state (Fe²⁺/Fe³⁺) in glass matrices

• Quality Assurance & Control (QA/QC)

Our Strengths

• Ideal for measuring concentrations of various analytes in solution

• UV/VIS/NIR quantification is simpler and less time-consuming than chromatographic analysis for solution-phase analytes

Limitations

• Other components in solution may cause spectral interference

• Chromatographic methods typically provide greater accuracy and precision than UV/VIS/NIR techniques

• Specific sample size/volume requirements apply (refer to technical specifications)

UV/VIS/NIR Technical Specifications

• • Wavelength Range：175-3300 nm (175-2500 nm when using integrating sphere)
  • Beam Dimensions：Diameter: 2 mm to 12×8 mm rectangular
  • Sample Size (Solid)：0.5×0.5 cm to 10×10 cm
  • Sample Volume (Liquid)：Minimum 0.2 mL