Mercury Sulphide Spectral Line Source

Spectral lamps find a home in special laboratory applications where they are commonly employed as stable, high quality sources of discrete spectral lines. Atomic spectra were originally produced either by creating an arc between electrodes fabricated of the metal to be studied, or by sprinkling a powdered salt into an ordinary gas flame. Both methods produce somewhat unstable results and require constant attention. In the 1940s a range of electric discharge lamps was developed to supersede these crude methods, and could guarantee superior results by virtue of the high purity of the metals contained within the discharge tube.

This lamp contains an unusual dose of mercuric sulphide to provide a contrast with the ordinary spectral output of the pure mercury discharge. This was presumably created to allow spectroscopic analysis either of the sulphur radiation, or possible some molecular radiation. Sulphur is notoriously corrosive towards metallic electrodes unless very special precautions are taken and special alloys are used, however in this lamp it is expected that an excess of mercury has been added to ensure that in the cooler regions of the electrodes, any sulphur would be present in molecular form.

The discharge tube is fabricated of quartz and includes platinised end chambers to prevent heat loss and ensure complete vaporisation of the dose. Unusual seals to tungsten wires have been employed instead of the usual moly foil pinch-seal, perhaps again to form a more corrosion resistant assembly. Clearly the lamp is intended to allow a study of the deep ultraviolet spectral regions since it is provided with a hole in the side of the UV-absorbing outer bulb. A single auxiliary starting electrode is provided.

Manufacturer:	Osram GmbH
Lamp Power:	50 Watts
Lamp Current:	1.1 Amps
Lamp Voltage:	50 Volts
Cap:	P28s/28 nickel plated brass
Bulb Finish:	Clear soda-lime (with hole transmitting to 220nm)
Bulb Type:	T-31
Overall Length:	155 mm
Light Centre Length:	75 ± 3 mm
Electrodes:	Secret sulphur-resistant alloy
Inner / Outer Atmosphere:	Inner: Ar \| HgS	Outer: Vacuum
Luminous Int. / Brightness:	5.0 candela	12.0 stilb
Luminous Area:	20 x 2 mm
Colour Temperature & CRI:
Chromaticity Coordinates:
Burning Position:	Vertical cap down
Rated Life:	100 hours
Warm Up / Re-strike Time:	10 minutes	Instantaneous
Factory:	Berlin, Germany
Date of Manufacture:	January 1953 (mex)


References:	1) Osram Spectral Lamps technical data sheet, 1960