Electronics Geeks: Identify This Light

Factual Questions
1
      • I was reading an article ages ago about some new type of light (the sulfur ones I think) and it had a quick review of all the other types of lights that had been invented. It mentioned one (from the past) that consisted of a metal plate that was excited with high-frequency electricity, and that directly gave off nearly-monochromatic light with very little heat produced. The color of the light depended on the frequency of the electricity, and the article noted that this invention never achieved practical use but that it had a significant influence on the understanding of the physics of light at the time. This wasn’t anything recently found, it was historical–many decades ago. I can’t remember the inventor’s name or the name of the light however, and I am curious. Anybody ever heard of such a thing?
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2

Sounds like an electroluminescent panel.

3

That was my first thought too, but EL panels don’t change color in response to changing frequency. The type of phosphor used in the panel determines the color.

4

I think that depends on the precise chemistry of the panel. From link:

5

I stand corrected. I think you got it.

Does anyone know the mechanism of this color change?

6

According to Squink’s link* it does respond to frequency changes:

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