Principle  

• When light is shone on different compounds, maximum absorption occurs at specific wavelengths

• Ultraviolet light has a shorter wavelength than visible light (200nm/300nm) 

• This allows it to detect functional groups of compounds and their concentrations 

Sample Spectrum 

Process 

• In order to examine a sample of a compound it must either be in a gaseous state or in solution (if it is a solid).

• This sample is then put into the chamber of the Ultraviolet Spectrometer.

• Light is then shone from a monochromatic source at the sample in the sample compartment.

• The light that is not absorbed by the sample is reflected onto the detector

• This process is repeated using lights of different wavelengths

• The wavelength at which maximum absorption occurs indicates what species the sample is.

U.V.Spectrometer Schematic

Applications

ORFEUS; Orbiting and Retrievable Far-reaching Extreme Ultraviolet Spectrometer...used...

• To determine the scattering properties of the lower planetary atmospheres. 
• To determine the distribution of constituents with height. 
• To determine the extent and distribution of hydrogen corona of the planets and satellites. 
• To investigate night airglow and auroral activity. 
• To determine the UV scattering properties and optical depths of planetary rings. 
• To search for emissions from the rings and from any ring "atmosphere.