UVVisNIR

UVVisNIR refers to spectroscopy that covers ultraviolet, visible, and near-infrared wavelengths, typically from about 190 or 200 nanometers up to around 2500 nanometers, though the exact range depends on the instrument. It is used to study the interaction of matter with light in these regions, primarily through absorption, transmission, or reflectance measurements.

In a UVVisNIR instrument, a light source emits a broad spectrum that is directed through or onto a sample. The light is dispersed by a monochromator or a spectrograph and detected by sensors such as photomultiplier tubes for the UV and visible ranges or silicon and InGaAs detectors for the near-infrared. Some systems use an integrating sphere to measure diffuse reflectance from powders or opaque materials. Instruments can operate in single-beam or double-beam configurations and may perform scanning measurements or use array detectors for rapid data acquisition. Sample preparation and optical geometry influence measurements, especially in scattering samples.

The core data are absorbance or transmittance spectra, which in many cases are interpreted using the Beer-Lambert law to estimate concentrations or determine extinction coefficients. Data processing may include baseline correction, smoothing, and derivative analysis to resolve overlapping bands.

Common applications span chemistry, materials science, pharmaceuticals, and biology. UVVisNIR spectroscopy is used for qualitative identification of substances, quantitative analysis of solutions, characterization of pigments and dyes, assessment of electronic structure in semiconductors, and monitoring of reaction kinetics. Limitations include band overlap, scattering effects, and dependence on sample state and geometry.