Greetings,
This post is about an application of a mixture of the common gases, Helium and Neon; namely the He/Ne Laser. It is well known that an electrical discharge can be made to travel the length of a partially evacuated tube. We see this in the form of fluorescent lighting. A similar electrical discharge is used to "excite" gas atoms within a He/Ne Laser tube.
Normally, an excitation of gaseous atoms to an elevated energy state will result in the emission of a mixture of energies across the visible light spectrum. In the case of the He/Ne Laser an additional process is occurring. As it turns out, Ne absorbs the electrical discharge at a slightly higher energy level than He. Typically, the amount of He used is ten times the amount of Ne inside the lasing device. There are two He higher energy states involved and the higher of the two, which dominates, is "long-lived". When the laser device is turned on, most of the He atoms have excited electrons in the higher energy long-lived state. These higher energy He atoms collide with Ne atoms and transfer enough energy to "push" Ne atom electrons up to its "slightly higher" energy state. Very soon, the majority of Ne atoms present are in an excited state and we have a "population inversion". The excited Ne atoms then rapidly return to a lower energy state with the emission of red light at a single wavelength (aka monochromatic light). The red light bounces longitudinally through the laser tube until a certain "threshold" is reached and the red laser light beam is seen exiting through the device lens. The process continues for as long as the electrical discharge is present. The process is shown visually in the image below.
So, there you have it!; a very interesting application of two common noble gases, the He-Ne Laser!
As always, thank you for reading!
A Publication of http://ExcellenceInLearning.biz
This post is about an application of a mixture of the common gases, Helium and Neon; namely the He/Ne Laser. It is well known that an electrical discharge can be made to travel the length of a partially evacuated tube. We see this in the form of fluorescent lighting. A similar electrical discharge is used to "excite" gas atoms within a He/Ne Laser tube.
Normally, an excitation of gaseous atoms to an elevated energy state will result in the emission of a mixture of energies across the visible light spectrum. In the case of the He/Ne Laser an additional process is occurring. As it turns out, Ne absorbs the electrical discharge at a slightly higher energy level than He. Typically, the amount of He used is ten times the amount of Ne inside the lasing device. There are two He higher energy states involved and the higher of the two, which dominates, is "long-lived". When the laser device is turned on, most of the He atoms have excited electrons in the higher energy long-lived state. These higher energy He atoms collide with Ne atoms and transfer enough energy to "push" Ne atom electrons up to its "slightly higher" energy state. Very soon, the majority of Ne atoms present are in an excited state and we have a "population inversion". The excited Ne atoms then rapidly return to a lower energy state with the emission of red light at a single wavelength (aka monochromatic light). The red light bounces longitudinally through the laser tube until a certain "threshold" is reached and the red laser light beam is seen exiting through the device lens. The process continues for as long as the electrical discharge is present. The process is shown visually in the image below.
So, there you have it!; a very interesting application of two common noble gases, the He-Ne Laser!
As always, thank you for reading!
A Publication of http://ExcellenceInLearning.biz
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