Timeline for Do all objects at the same temperature glow the same color?
Current License: CC BY-SA 4.0
9 events
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| Nov 22, 2022 at 11:39 | comment | added | sh4dow | The neon atoms will give off some thermal radiation, but in a gas the interactions between atoms are comparatively rare and the amount of emitted radiation is therefore very low (the volume absorption (or emission) coefficient is very small). | |
| Nov 20, 2022 at 23:08 | comment | added | James | @sh4dow Thank you. In the case of of a tube of neon gas, besides emitting specific wavelength signatures due to electrons jumping from higher to lower orbitals, why don't the collection of neon atoms as a whole, which must be vibrating at current temperature, also give off Kirchoff's thermal motion radiation, thus contaminating the pure atomic spectra lines for neon? | |
| Nov 20, 2022 at 18:46 | comment | added | sh4dow | And perhaps I should add that structures with optically interacting materials can have a thermal based emission unlike the Planck spectrum: Eg. an infrared reflecting layer would reduce the emissivity of the "system" in the infrared spectrum and leave the non-infrared emissivity untouched. And if you just describe the apparent properties of complex materials, you often get nonuniform emissivities. But you can view these systems as emitting a planck spectrum that is then modified by the optical properties of the system. | |
| Nov 20, 2022 at 18:18 | comment | added | sh4dow | @Jasen I circumvent the complexities of absorption/emission spectra by clearly separating thermal and non-thermal components of light emission. The thermal component is universal (in form, not in magnitude), the non-thermal one is usually highly specific. | |
| Nov 20, 2022 at 18:14 | comment | added | sh4dow | @James that kind of light emission comes from electrons being pushed to a higher energy orbital and spontaneously jumping back down while emitting the energy difference as a photon. This is why there are specific signatures - since electron orbitals have specific energy values, emitted photons always have the energy of a specific difference of two orbitals. Kirchhoff's law applies to thermal spectra, which come from the thermal motion of atoms. | |
| Nov 20, 2022 at 10:15 | comment | added | Jasen | no this is wrong. black bodies follow the black body profile, coloured bodies basically emit the colours they don't reflect. - as in "the sympathizer"'s answer | |
| Nov 19, 2022 at 13:12 | comment | added | James | Thank you. Does the glow that a neon gas tube, or sodium gas tube, or hydrogen gas tube emit when passed with electricity constitute "thermal radiation", or something else? Why is there a specific signature for each atom's spectrogram, would it not contradict Kirchoff's law that spectra depends entirely from temperature? | |
| S Nov 19, 2022 at 12:50 | review | First answers | |||
| Nov 19, 2022 at 13:42 | |||||
| S Nov 19, 2022 at 12:50 | history | answered | sh4dow | CC BY-SA 4.0 |