In a scientific demonstration of volcanic eruption(decomposition of ammonium dichromate), the green chromium(III) oxide produces an orange spark to mimic the eruption of lava from a volcano.

I would like to know how the spark is produced. Is it due to the release of photon when the excited state returns to the ground state?


1 Answer 1


The mechanism of spark shining is the same as the mechanism of the orange glow in the core of the "volcano" - thermal radiation of solid bodies.

Sparks are just dust particles of mostly Chromium(III) oxide, going upwards due intense thermal convection and by local mechanical effects of self-burning of crystals.

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    $\begingroup$ To prove that point, use a diffraction grating or hand-held spectroscope -- if the spectrum is continuous, it's thermal, and if there are lines, then I'd be excited to see the results of that experiment -- post it here as an answer. $\endgroup$ Dec 10, 2023 at 19:26
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    $\begingroup$ Sure. Send me the device. $\endgroup$
    – Poutnik
    Dec 10, 2023 at 19:40
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    $\begingroup$ That comment was for the OP ;-) BTW, hand spectroscopes are ~US$2.5 at Amazon and AliExpress. $\endgroup$ Dec 10, 2023 at 21:26
  • $\begingroup$ @DrMoishePippik It was hard to imply without the explicit user reference. :-) // The point is, sparks of any kind are not gas based to have a line spectrum. $\endgroup$
    – Poutnik
    Dec 10, 2023 at 21:40
  • $\begingroup$ P.S. Obviously except electric arcs and similar, that are rather a plasma $\endgroup$
    – Poutnik
    Dec 11, 2023 at 7:51

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