Excimer-laser light locks tritium into silica for micropower

In the interests of creating on-chip radioisotope micropower sources, researchers at the University of Pittsburgh (Pittsburgh, PA), the University of Toronto, and Kinectrics (both of Toronto, Ont., Canada) have locked tritium, the gaseous radioactive isotope of hydrogen, into silica glass using 248 nm light from a krypton fluoride excimer laser.

In the interests of creating on-chip radioisotope micropower sources, researchers at the University of Pittsburgh (Pittsburgh, PA), the University of Toronto, and Kinectrics (both of Toronto, Ont., Canada) have locked tritium, the gaseous radioactive isotope of hydrogen, into silica glass using 248 nm light from a krypton fluoride excimer laser. While tritium can be loaded into fused silica without the help of laser light, the excimer radiation keeps the gas from diffusing away.

A silica film on a silicon substrate was loaded by exposing it to tritium at a pressure of 12.4 megapascal and 250°C for anywhere from two hours to seven days. Excimer-laser light at a fluence of 4800 J/cm2 bonded 60% of the permeated tritium to the glass, versus 10% for non-laser-irradiated samples. The locked tritium remained in the glass even at temperatures up to 400°C. A tritium-loaded film on a chip would produce energetic electrons that could charge up a capacitor for power, or excite or ionize molecules. The researchers created a 0.5 cm2 tritium-loaded film, placed it between two electrodes, and measured a nanoampere-level ionization current. Contact Baojun Liu at bal4@pitt.edu.

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