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LIGHT SOURCES IN UV-VIS SPECTROMETRY, double-beam-uv-vis-spectrophotometer…
LIGHT SOURCES IN UV-VIS SPECTROMETRY
Deuterium arc
lamp
ultraviolet region (190-400 nm)
A discharge light source with several hundred Pa deuterium sealed in a bulb
Uses a hot cathode to achieve stable and reliable arc discharge, approximately 10 sec for preheating is required before starting the discharge
Aperture gives 1-1.5 mm spot
low noise characteristics (that can be the limiting factor when it comes to noise performance in a spectrophotometer)
Service life of typically 1,000 hours
Require a large and complex power supply, :warning:
However, it is one of the few continuous spectrum light sources that is stable in the ultraviolet range :check:
More expensive than a halogen lamp
Most common UV source
Xenon Arc Lamp
A discharge light source with xenon gas sealed in a bulb
:
Inferior in term of cost
Exhibits a similar spectral distribution to sunlight
Used in cases where a high light intensity is required due to high brightness
Region : 185-2000 nm
Provides high energy light source, and it can reach a steady state in a short time period
Tungsten/Halogen Lamp
Also known as Quartz iodine lamp
Visible region: 320 - 1100nm
Tungsten-halogen source can operate at higher temperature and give off more UV light
used as the filament material evaporates at high temperatures
A capsule that holds a special halogen gas (such as iodine or bromine) mixed with inert gas around the heated filament to increase the efficacy of the incandescence
halogen lamp filament heats up and emits light when a current flows through it
General halogen lamp life is about 2000 hours or more.
Cheap
Light Emitting Diodes (LED)
narrow band continuous light emitting diode source
Region ：240-360 nm
High output power is needed,
They provide long lifetime, short warm-up time and high-stability.
Low maintenance cost
cheap with a long lifetimes and a small environmental impact
Produce a single wavelength of light, thus, does not require a monochromator
