Ultraviolet Visible Spectroscopy: A Technique for Analysing Minerals and Rocks
UV visible spectroscopy is a powerful analytical tool that can be used to determine the composition of minerals and rocks. It is an expensive tool, though, and most laboratories don’t own or use it frequently enough to justify spending hundreds of dollars on a single sample.
Instead, many laboratories opt for cheaper alternatives such as cuvettes. A UV-vis cuvette is a small glass tube into which a sample is dropped and then subjected to UV light in order to analyse its composition.
To learn how this technique works and its potential uses, you’ll need the following: • An understanding of the properties of UV light
- Basic knowledge of minerals
- A basic understanding of how solids react to UV light
Typically, you will drop a small part (typically one-fifth of the total volume) of the sample into the cuvette and let it fall through the light into a spectrometer. The rest of the sample (usually the remainder of the container) is then observed using a same-day vision lens or another type of optical microscope.
The quality of the sample is crucial for accurate analysis, and you should be sure to collect it as close to the origin of the light as possible.
Inspecting the origin of the light in UV visible spectroscopy is to analyze the color of the light. The wavelengths of light that can be detected by the spectrometer are those that are contained within the visible range (400–600 nm).
There are many different types of cuvettes: For example, a simple glass cuvette can be used for solid samples like rocks.
More expensive cuvettes allow you to collect a wider range of samples, including liquids and gases. In order to collect a sample with a cuvette, you will need to know the following:
- The volume of the sample to be analyzed
- The type of cuvette (simple, mixed, or confocal)
- The nature of the sample (solid, liquid, or gas)
- The sample’s concentration
The volume of the sample is determined by adding a mouthpiece to the bottom of the cuvette. This mouthpiece can be made out of plastic, foil, or some other material that is impermeable to the sample.
The type of cuvette (simple, mixed, or confocal) is determined by how you plan on analyzing the sample. A simple cuvette is just a glass tube without any internal components. This type of cuvette works great for detecting simple substances like chemicals or minerals.
A mixed cuvette contains both solid and liquid components. A confocal cuvette is a special type of glass cuvette that allows for the analysis of small volumes of liquids.
The nature of the sample (solid, liquid, or gas) is determined by how you want to analyze it. For example, you can place the sample in a tube with a small amount of gas (such as air) to detect the presence of nitrogen.
Alternatively, you can place the sample in a liquid (such as water) to detect the presence of chemicals. The sample’s concentration is determined by adding a known amount of liquid (for example, water) to the cuvette to make the volume equalized.
Once the volume is equalized, the light from the sample is split, with one half being collected inside the cuvette and the other half being reflected off the sides.