Near Infrared Emission from Metal Halide Lamps with Rare Earth Salts
Abstract
A Fourier transform infrared (FTIR) spectrometer is being used to study gas phase near-IR emission from Metal Halide-High Intensity Discharge (MH-HID) lamps with doses containing rare earth salts. Spectral limits of resolution down to 0.125 cm-1 are adequate to fully resolve pressure broadened features from MH-HID lamps in both spatially resolved and spatially averaged measurements. Near-IR emission spectra are dominated by atomic line emission, not molecular bands as first expected. A similar result was found for MH-HID lamps with Na/Sc salts [1]. Although the most reliable absolute measurements require the use of a gold-coated IR integrating sphere, the broad spectral coverage of the FTIR makes it possible to perform an internal absolute calibration of the near-IR emission by comparing the near-IR emission to the mid-IR "black body" emission of the fused silica arc tube. The emissivity of fused silica is near one from 1200 to 2400 cm-1 and thus its emission in this range is well understood. Additional work with an IR integrating sphere is needed, but the total near-IR emission from lamps with rare earth salts seems to be lower than the 20 -30expected. [1] D. J. Smith, G. A. Bonvallet, and J. E. Lawler, J. Phys. D: Appl. Phys. in press.
- Publication:
-
APS Annual Gaseous Electronics Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..GECMW1002L