What is the Difference Between UV Vis and Fluorescence Spectroscopy?

UV-Vis and fluorescence spectroscopy are both analytical techniques that involve the use of ultraviolet and visible light. However, they differ in the way they measure light and the phenomena they study. The key difference between the two is:

• UV-Vis Spectroscopy: This technique measures the absorption of light by a compound as a function of wavelength in the UV-visible range (200 to 400 nm and 400 to 750 nm). It involves passing a beam of light through a sample and measuring the amount of light absorbed by the sample. This method is useful for studying the properties of different chemical substances and their concentrations.
• Fluorescence Spectroscopy: This method measures the light emitted by a sample in the fluorescence range after absorbing light at a higher energy than it is emitting. In fluorescence spectroscopy, the sample is illuminated from the side through the rough side of the cuvette, which scatters the light throughout the sample. The detector measures the emitted light, typically in the visible range (400 to 750 nm). Fluorescence spectroscopy is often considered to be more sensitive than UV-Vis spectroscopy because it is an absolute measurement, meaning that single photons can be measured against a 'dark' background.

Both UV-Vis and fluorescence spectroscopy are used to study the properties of different chemical substances, but they do so through different phenomena, with UV-Vis measuring the absorption of light and fluorescence measuring the emission of light after absorption.

Comparative Table: UV Vis vs Fluorescence Spectroscopy

The main difference between UV-Vis and fluorescence spectroscopy lies in the measurement of light. UV-Vis spectroscopy measures the absorption of light in the ultraviolet-visible range, while fluorescence spectroscopy measures the light emitted by a sample in the fluorescence range after absorbing light at a higher energy than it is emitting. Here is a table comparing the two methods:

Both UV-Vis and fluorescence spectroscopy are used to study the properties of different chemical substances. UV-Vis spectroscopy is more common and widely used in various fields, including food analysis. Fluorescence spectroscopy, on the other hand, is more sensitive and can provide more detailed information about molecules' energy levels and electron transitions.