Mercury lamp - Suigintou

A light source that utilizes the light emitted when a discharge is caused in mercury vapor. Differences in the mercury vapor pressure during the discharge result in differences in the emission wavelength.
(1) Low-pressure mercury lamp. A mercury lamp contains a single drop of mercury and several hundred Pa of argon or neon to aid in the discharge. When discharged at a low current, it emits mainly resonance lines (253.7 nm and 184.9 nm). It also emits a weak visible light at 435.8 nm.
(2) High-pressure mercury lamps. They are designed so that the mercury pressure when lit is about 1 atm. The emission wavelength is strongest around 365 nm, with the visible range consisting of 579, 577, 546, and 436 nm. As a light source, they are used in combination with filters. The resonance lines are inverted and almost invisible.
(3) Ultra-high pressure mercury lamps. Mercury is sealed in a quartz capillary and a high-density electric current is passed through it, which increases the mercury pressure to several tens of atm. This broadens the linewidth of the emission line, making it a continuous wavelength light source that covers the ultraviolet to visible wavelengths.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

水銀蒸気中に放電を起こさせたときの発光を利用する光源．放電中の水銀蒸気圧の違いによって発光波長に違いが出てくる．
(1)低圧水銀灯．水銀一滴と放電を助ける数百 Pa のアルゴンやネオンを封入した水銀灯．低電流で放電させると，おもに共鳴線(253.7 nm と184.9 nm)を発光する．可視部は弱い435.8 nm の発光である．
(2)高圧水銀灯．点灯中の水銀圧が1 atm 程度になるように設計されている．発光波長は365 nm 付近がもっとも強く，可視部は579，577，546，436 nm などからなっている．光源としてはフィルターと組み合わせて使用される．共鳴線は反転していてほとんど見えない．
(3)超高圧水銀灯．石英製の毛管中に水銀を封入し，高密度の電流を流すことによって水銀圧が数十 atm にもなる．このため，発光線の線幅が広がり，紫外から可視にかけての連続波長光源になる．

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