Tuning an emission spectrum

[eeka chu]

Is there anyway of manipulating the emission spectrum of something like a gas by pumping it with a specific input?

An argon gas laser, for example, will have lots of emission lines. Is there anyway of singling out groups of those lines without changing the gas? I would imagine such a method would have something to do with the frequency of the pumping current, the energy levels of the electrons or some of both; e.g. by increasing the voltage you'd get more high energy electrons which would seem to suggest more of the higher energy lines would be then be stimulated.

Also, as a kind of side question, what kind of spectral bandwidths can excitation / emission lines have? If the lines were absolutes, things like atomic clocks would have problems locking the frequency - well, you'd need an absolutely identical excitation frequency - and a whole load of other things relying on such pumping wouldn't work very well, if at all. So the lines have widths, and that implies that there is some degree of 'tolerance' if you like on the energy taken up and re-emitted by electrons as they move between levels, that the values aren't perfectly discrete; which then, of coarse, allows their input / output lines to be thicker than single, absolute frequencies. For example... I might have a line that centres at 380nm but it also has a thickness that stretches a few nm either side of it. Those nm would indicate that there is a slight degree of variance occurring in the energy transitions that create the line. I'm going to take a guess that those variances follow a bell shaped curve of distribution a la energy per particle against temperature.

Thanks!
John

 

[pervect]

I know that dye lasers are fairly tunable, but not much about the specifics.

 

[sir-pinski]

Yes, there are ways to manipulate the emission spectrum of a gas by pumping it with a specific input. This process is called "tuning" and it involves changing the energy levels of the electrons in the gas through various methods such as varying the voltage or current of the pumping source. By doing so, specific emission lines can be enhanced or suppressed, resulting in a desired emission spectrum.

One method of tuning is called "mode locking" where the pumping source is synchronized with the natural oscillation frequency of the electrons in the gas, resulting in a more narrow and intense emission spectrum. Another method is "dye tuning" where a dye is added to the gas, which selectively absorbs certain wavelengths of light and enhances specific emission lines.

In terms of spectral bandwidths, excitation and emission lines can have a range of widths depending on the specific gas and conditions. As you mentioned, these lines are not perfectly discrete and can have some degree of variance. This is due to factors such as temperature, pressure, and the specific energy levels of the electrons involved. However, these variances can be minimized through precise control of the pumping source and conditions, allowing for more accurate and reliable measurements in applications such as atomic clocks.

In conclusion, there are various methods of tuning the emission spectrum of a gas, allowing for specific emission lines to be enhanced or suppressed. The spectral bandwidths of these lines can vary, but can be controlled through precise adjustments and conditions.