How do you estimate the instrumental line width in emission spectroscopy experiments? Do we need calibration lamp of some sort?
I usually use a He-Ne laser with a scattering sample. When we still had an argon laser in the lab, I used that too.
Well, I do not need resolution better than 0.1 nm in UV-Vis-NIR range. Instruments capable to resolve superfine structure of atom emission definitely need completely different calibration - since you did not specify what your demands are ;-)
I have a spectrometer with resolution 0.2 nm. Shall I shine He-Ne laser into it and measure the width?
You need a spectroscopic line, which is much more narrow than your instrumental profile. In advance you do not know which line it can be. Instrumental profile also depends on wavelength, so the line (better several) should be in the wavelength region of interest. Special calibration lamps are exist but it would be interesting for high resolution spectrometers which are not popular in our days.
For low resolution spectrometers (0.2 nm) any low pressure discharge in atomic gas can be suitable (for example He-Ne laser, but direct laser radiation can destroy the detector). LOT Pen-Ray lamps are very useful for wavelength calibration and can be a good estimation of the low-resolution instrumental profile. I use normally several lamps (Xe, Hg+Ar, Ar, Ne) depending on spectrometer and practical task.
Observation of fluorescent lamps which are used now everywhere can be useful as well but subtraction of the luminophore continuum might leads to ambiguous results.
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