UV-Visible spectroscopy involves light sources that emit visible and/or ultraviolet radiation. The molecular/atomic transitions that are involved are associated with electronic transitions. Since ordinary glass absorbs ultraviolet radiation, quartz or other UV-transparent materials must be used inside the spectrometers and sample holders.

Spectroscopy depends on the absorption of light as electrons change energy levels.

Spectronic 20™ is a simple instrument which is usually used at one or two wavelengths.

Scanning spectroscopy automates the process of recording absorption as a function of the wavelength.

Modern high end spectrometers use CCDs to record a range of wavelengths simultaneously.