Atomic Spectrometry: Sharp Atomic Spectrum & Noise Reduction

[goggles31]

I read that a hollow cathode lamp is preferable to a continuum light source since it emits a sharp atomic spectrum and hence the noise is lower. Could someone please explain how the noise is affected by the sharpness of the atomic lines?

Also would you expect only the colours corresponding to the element to be emitted from the lamp or do the fill gas atoms emit light too? So the only wavelengths emitted are from these atoms, am I right? Thank you for your time.

 

[Simon Bridge]

Could someone please explain how the noise is affected by the sharpness of the atomic lines?

If there was high noise, the line would be fuzzy.

Also would you expect only the colours corresponding to the element to be emitted from the lamp or do the fill gas atoms emit light too? So the only wavelengths emitted are from these atoms, am I right?

That is almost correct. A lamp relying on a discrete spectrum process will only emit wavelengs according to the atomic spectra - not pure white light. You may notice that cheap commercial lamps working on the principle have a slight tint to them.
However, manufacturers usually paint a layer of phosphor (or something) on the inside of the bulb, and/or include several different kinds of atom, so the combined colour can be tuned.