發射光譜是根據激發原子的種類與放電電漿的壓力而定 . 不過 , 第一代的汞蒸氣電弧燈的確發出藍綠色光 .
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http://en.wikipedia.org/wiki/High-i..._discharge_lamp
Types of HID lamps include:
Mercury vapor (CRI range 15-55)
Metal halide (CRI range 65-80, ceramic MH can go to 90s)
Low-pressure sodium (CRI 0 owing to their monochromatic light)
High-pressure sodium (CRI range 22-75).

Mercury vapor lamps, which originally produced a bluish-green light, were the first commercially available HID lamps. Today, they are also available in a color corrected, whiter light. But they are still often being replaced by the newer, more efficient high-pressure sodium and metal halide lamps. Standard low-pressure sodium lamps have the highest efficiency of all HID lamps, but they produce a yellowish light. High-pressure sodium lamps that produce a whiter light are now available, but efficiency is somewhat sacrificed. Metal halide lamps are less efficient but produce an even whiter, more natural light. Colored metal halide lamps are also available.

第一代商業化 HID 是產生藍綠光的汞蒸氣放電燈, . 今日的也有經過色偏校正過/光色較白的汞蒸氣放電燈. 但是汞燈往往被新一代效率更高的高壓鈉燈與鹵化金屬燈所取代. 在所有的 HID 燈具中, 標準低壓鈉燈的發光效率最高, 但是只能發出黃光 . 目前也有發光效率較差, 光色較白的的高壓鈉燈. 還有發光效率更差, 光色更白更接近自然光的鹵化金屬燈. 目前也能買到發出彩色光的鹵化金屬燈.

http://en.wikipedia.org/wiki/Mercury-vapor_lamp
Even at full intensity, the light from a mercury vapor lamp with no phosphors is distinctly bluish in color.

Color considerations
To correct the bluish tinge, many mercury vapor lamps are coated on the inside of the outer bulb with a phosphor that converts some portion of the ultraviolet emissions into red light. This helps to fill in the otherwise very-deficient red end of the electromagnetic spectrum. These lamps are generally called "color corrected" lamps. Most modern mercury vapor lamps have this coating. One of the original complaints against mercury lights was they tended to make people look like "bloodless corpses" because of the lack of light from the red end of the spectrum. There is also an increase in red color (e.g., due to the continuous radiation) in ultra-high pressure mercury vapor lamps (usually greater than 200 atm.) which has found application in modern compact projection devices.

Emits Wavelengths - 253.7, 365.4, 404.7, 435.8, 546.1, and 578.0 nm.
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