UVVisspectrometers

UV–Vis spectrometers are analytical instruments that measure how much ultraviolet and visible light a sample absorbs or transmits across a defined wavelength range. They are used to identify substances and to quantify concentrations based on the relationship between absorbance and path length and concentration (Beer–Lambert law).

A typical instrument consists of a light source, a wavelength selector (monochromator), a sample compartment with cuvettes, and a detector, plus a signal processor and software. Many modern instruments are diode-array spectrophotometers that collect spectra at all wavelengths simultaneously, while traditional models are single-beam or double-beam instruments that scan one wavelength at a time. Light sources include a deuterium lamp for the UV and a tungsten-halogen lamp for the visible; sometimes a combined source is used. The monochromator uses a diffraction grating or prism to select wavelength. Detectors may be photodiodes, photomultiplier tubes, or CCD arrays. Cuvettes are typically quartz for UV measurements or glass for visible, with standard path lengths such as 1 cm.

Measurement modes and data: The instrument typically reports absorbance (A) or percent transmittance (%T); transmittance is related to absorbance by A = -log10(T). Wavelength range commonly spans about 190 to 900 nm, with some instruments extending into the near-infrared. Spectral resolution and wavelength accuracy vary by design. Data can be used to generate calibration curves for concentration measurements and to analyze sample composition.

Applications: UV–Vis spectrometers are widely employed in chemistry, biochemistry, environmental monitoring, pharmaceuticals, food and beverage analysis, and materials science. Common tasks include concentration determination via standards, assessment of purity, reaction monitoring, and qualitative identification based on spectral features.