Why is the spectrum of a blue flame the way it is?

Question

In the spectrum of the blue part in a candle flame, there’s a violet emission at 432 nm due to excited CH* molecules (chemiluminescence). Why 432? Why not 400 or 500? There are emissions at 436, 475 and 520 nm too. Why these numbers? Is it because the energies of the photons emitted correspond to these wavelengths, as E = hc/λ?

score 0 · Answer 1 · answered Mar 15 '15 at 13:17

0

Yes. And because those energies correspond to differences in energy between bonds in CH and C2 and bonds in the CO2 and H2O reaction products.

answered Mar 15 '15 at 13:17

mmesser314

49,702

score 0 · Accepted Answer · edited Mar 20 '15 at 13:19

0

Atoms and small molecules have discrete energetic states. When an excited molecule relaxes to the ground state by emitting a photon, the energy (wavelength) of this photon is equal to the energy difference between the 2 states.

edited Mar 20 '15 at 13:19

Michael Dy

187

answered Mar 17 '15 at 08:51

gigacyan

4,740
1
23
31

Why is the spectrum of a blue flame the way it is?

2 Answers2