Vaporization of Tungsten Studied by Flash Heating and Kinetic Spectroscopy. I. Near‐Ultraviolet Region

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Abstract
Thin wires or strips of tungsten have been vaporized by heating with an intense pulse of light from a capacitor discharge lamp. The appearance of the metal as it vaporizes has been recorded by high‐speed photography; the characteristics of the vapor were studied at various times by kinetic absorption spectroscopy. When flash heated, tungsten behaves grossly like an electrically exploded metal. Using an approximate spectroscopic method, we have estimated the electronic temperature of the vapor to be near 3000°K as it sublimes from the solid, and near 7000°K as it boils from the liquid. Thermal excitation of nearly 22000 cm—1 occurs under the latter conditions. Production of tungsten ions seems negligible. Some secondary photoexcitation of the atoms to states lying as high as 55000 cm—1 may occur. Flash heating shows promise as a general method for producing vapors of even the most refractory elements for absorption spectroscopy.