Light : fluorescent 152 neon

The primary use of xenon is in lamps. When an electric current is passed through a gas, it can give off light. Fluorescent lamps and neon lights are examples of this process. The kind and color of light given off depend on the gas used in the lamp. 

Another state of matter is plasma, which consists of positive ions and free electrons in a gaslike state. Examples of plasmas include the substances inside fluorescent lights and neon signs. 

Gas lasers are not unlike fluorescent light bulbs and neon signs. Gas is confined to a hollow tube, and electricity passing through it excites the atoms. The most common gas lasers use carbon dioxide, argon, and helium-neon. Gas lasers are relatively inexpensive and can produce very high-powered beams. 

FIGURE 15.25 The colors of this fluorescent lighting art hv Tom vnl noble-gas atoms. Neon is responsible for the red light i > li... 

Strip lighting in a classroom, hospital, business hall or kitchen is often called fluorescent lighting, although in fact it is a phosphorescent process, as above. Each bulb consists of a thin, hollow glass tube that is sealed at both ends. It contains gas such as helium, argon or krypton, and a drop of liquid mercury (about 0.5 mg of mercury per kilogram of lamp, or 0.5 parts per million). Like the neon and sodium lamps above, the pressure inside the tube is about 30 Pa, so the mercury evaporates to become a vapour. It is the mercury that yields the light, albeit indirectly. 

Louis A. Bloomfield s entertaining book How Things Work The Physics of Everyday Life (second edition), Wiley, New York, 2001, discusses neon bulbs and fluorescent strip lighting, see pp. 395-399. For a more scientific look at fluorescent dyes, try Chapter 3 of Peter Bamfield s Chromic Phenomena (above), especially pp. 182-184. 

FIAs can be based on steady-state intensity measurements without probe amplification, owing to the sensitivity of detection that is possible with fluorescence instrumentation, which exceeds that of spectrophotometers by two or three orders of magnitude. A sensitive fluorometer has been described for an estradiol assay(36) in which the limit of estradiol detection is 3 x KT11 M. Estradiol antibody labeled with rhodamine B is reacted with estradiol samples. Unreacted labeled antibody is removed with Sepharose-estradiol-casein beads, and the remaining fluorescence is directly proportional to the analyte concentration. The detection limit of rhodamine B on the same fluorometer is 5 x 1(T12 M. This instrument uses a 0.75 mW green helium-neon (HeNe) laser to irradiate the sample from above, at the air-liquid interface, to increase the light path and to decrease surface reflections. The sample compartment has a top-mounted photon trap, and a mirror mounted on the side of the sample compartment opposite the PMT to enhance detection. 

What is the primary difference between the ways a neon light and a fluorescent light work ... 

Beryllium (Be) is in group 2A and is the first metal in the periodic table to be notably toxic. When fluorescent lamps and neon lights were first introduced, they contained beryllium phosphor a number of cases of beryllium poisoning resulted from the manufacture of these light sources and the handling of broken lamps. Modem uses of beryllium in ceramics, electronics, and alloys require special handling procedures to avoid industrial exposure. 

Krypton gas is also used in making neon lights. Neon lights are colored lights often used in advertising. They are similar to fluorescent... 

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