Dateikommentar: Spectrum of ST171 with h-beta line
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Starter Lamps with differents content (e.g. Ar, Ne, Xe ) can be used for wavelangth calibration. In some starter lamps e.g. Osram ST171 also hydrogen is present, which can be seen by prominent H-alpha/beta/gamma lines.
What´s surprising to me is, that these hydrogen lines have a FWHM much broader than the instrument resolution. As expected to me all Ne, Ar, Xe lines show a linewidth corresponding to the spectral resolution of my instrument.
I,m using a camera with 5,86 micron pixels and a glas fiber of 50 microns.
So hydrogen lines have a FWHM of about 0,27nm, Ne, Ar etc about 0,065 nm (=instrument resolution)
See also 2 samples of spectra below.
Does anybody have an explanation for this? What thermal and/or pressure conditions in these starter lamps are responsible for that?