Differences and uses of deuterium lamp, xenon lamp and mercury lamp

Gas discharge light source is a light source made by gas discharge principle.

Light source structure: tubular and spherical light bulb made of glass or Shi Ying. Electrodes are installed in the bulb, and light-emitting gases, such as hydrogen, helium, deuterium, xenon, krypton, or metal vapor, such as mercury, cadmium, indium, thallium, dysprosium, etc., are filled.
Gas discharge principle: gas excites electrons and ions under the action of electric field and becomes a conductor. Ions move to the cathode and electrons move to the anode, and energy is obtained from the electric field. When they collide with gas atoms or molecules, new electrons and ions will be excited, and gas atoms will be excited, and the inner electrons will jump to high energy levels. When excited electrons return to low energy levels, photons are emitted.
I. Deuterium lamp
Luminous mechanism: the bulb of deuterium lamp is filled with high purity deuterium gas. When the deuterium lamp works, the cathode emits electrons, and the high-speed electrons collide with deuterium atoms, exciting deuterium atoms to generate continuous ultraviolet spectrum (185～400 nm).
Application: Deuterium lamp has high ultraviolet radiation intensity, good stability and long life, so it is often used as a continuous ultraviolet light source for various ultraviolet spectrophotometers. It is high performance liquid chromatograph (HPLC), ultraviolet-visible spectrophotometer (UV), atomic absorption spectrometer (AA) and capillary electrophoresis instrument (CE).

Atomic spectrum lamp: hollow cathode lamp/element lamp
Luminous mechanism: Atomic spectrum lamp is also called hollow cathode lamp. The anode and cylindrical cathode are sealed in a glass shell, and there is a transparent Shi Ying window on the upper part of the glass shell. When working, the window transmits discharge glow, which is mainly the atomic spectrum of cathode metal. The current density of hollow cathode discharge can be more than 100 times higher than that of normal glow. Although the current is large, the temperature is not high, so the luminous spectrum is not only strong, but also very small in wavelength width.
Application: The main function of atomic spectrum lamp is to extract the beam of standard spectral line, determine the splitting position of standard spectral line, and determine the characteristic wavelength in absorption spectrum. It is mainly used in devices for spectral analysis of elements, especially trace elements.
Iii. Mercury lamp

Classification of mercury lamps: low-pressure mercury lamps, high-pressure mercury lamps and ultra-high-pressure mercury lamps.
Luminous characteristics of mercury lamp: The higher the air pressure of mercury, the higher the luminous efficiency of mercury lamp, and the light emitted from it also transits from linear spectrum to banded spectrum.
Low-pressure mercury lamp-the pressure of mercury vapor is 0.8Pa, which mainly radiates 253.7 nm ultraviolet light. Commonly used in wavelength reference, ultraviolet sterilization and fluorescence analysis of spectrometer.
High-pressure mercury lamp-the pressure of mercury vapor is (1-10)*10 to the fifth power Pa. The visible region shows a band spectrum, and the infrared region shows a weak continuous spectrum. Commonly used in ultraviolet irradiance standards, fluorescence analysis, ultraviolet flaw detection and large-area lighting.
Spherical ultra-high pressure mercury lamp-the pressure of mercury vapor is (10-20)MPa. The spectral line is wide, forming a continuous background, the visible region is blue, and the infrared radiation is enhanced. It is often used as a point light source in optical instruments, fluorescence analysis and lithography.
Four, xenon lamp

Luminous material: xenon.
Spectral characteristics: the spectral distribution is close to sunlight, the color temperature is 6000K, the brightness is high, and the service life can reach 1000 h..
Classification of xenon lamps:
Long arc xenon lamp-electrode spacing is 15 ~ 130 cm, thin tube shape, working pressure is 105 Pa, and it is used for large-area lighting in docks, squares, stations and so on.
Short-arc xenon lamp-the electrode spacing is in the order of several millimeters, and the working pressure is 1 ~ 2 MPa. It is a good sunlight color point light source and is often used in movie screening, color photography, photographic plate making, simulated sunlight and other occasions.
Pulsed xenon lamp-The air pressure in the tube is below 100 Pa, which is excited by high-voltage electric pulse to generate light pulse, which emits strong light in a very short time. Widely used in solid-state laser optical pump, photographic plate making, high-speed photography and optical signal source.