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Disclaimer: My background is computer science.

Is it possible to detect any gas using a visible light and near infrared (400 nm - 1000 nm) hyper spectral imaging camera? This can be related to gas leaks, pollution, gasses released in fires... From what I found when googling, this is not really possible, but I though to check here to be sure.

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    $\begingroup$ There are gases that absorb in the visible region. Some are nasty and not things you'd run into every day like bromine. The only thing that comes to mind that could be rigged up with a camera like that would be an NO2 detector. NO2 is red to brown colored and is major industrial pollutant. Accurately quantifying NO2 with a single modded camera doesn't seem likely or useful though. $\endgroup$ – airhuff Apr 4 '17 at 6:55
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The answer is that you can detect all types of gases if you have the correct light source and use Raman spectroscopy. Raman is more adaptable than absorption or emission spectroscopy as it is a scattering process and the laser does not have to operate at the wavelengths that the molecules absorb, thus one laser can be used for all samples. A suitable source is going to have to be a narrow band laser (although when Raman discovered this effect he used sunlight). You will also need notch -filters to remove the laser wavelength and prevent it from saturating your detector. Not cheap.

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This is a broad question and the answer depends on the type of gases and the type of spectroscopic technique.

  1. Absorption :The spectral region described by you refers to the visible region and some part of the infrared region. Hence, all colored gases can be observed. Some gases which absorb light in the lower infrared region 700 nm to 1000 nm region can also be detected. The principle of absorption is completely different in different regions of the electromagnetic spectrum (400-700 nm - electronic absorption, 700-1000 nm = vibrational absorption) and so the intensities will also be different. In this case a broad band light source is used as a source of incident light and the absence of certain wavelengths due to absorption is signal of some gases. (Colorless gases will not be detected in the visible region, though possible in the infrared region).

  2. Emission : Other spectroscopic techniques might be possible involving some excitation (using light in far UV - UV region), and then emission in the 400-1000 nm region and this emission is detected by the detector. Colorless gases can be easily detected by emission approach but requires expensive (and dangerous) UV light source(s).

Specifically which gases is being detected (by any approach) needs careful investigation by a chemist and probable comparison with already existing literature on absorption and emission of possible gases.

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