<p>Well,
I've pointed my spectrometer at my fireplace, and I can confirm the presence of a relatively strong sodium line(s). It just takes trace amounts of sodium to produce this signature, it cannot be mistaken.</p>
<p>I also see an emission band around 765~766nm, of unknown origin, though ProfRob points out below that it's likely to be potassium.</p>
<p>Don't mind the dots, those are hot pixels, my spectrometer is using a 100um slit and requires long exposure times. The sensor is an inexpensive OV2640, spectral lines calibration is within &lt;0.7nm but I'm still in the process of performing the spectral responsivity calibration. And it might still be slightly out of focus.</p>
<p>This instrument uses an actual transmissive grating, 500lines/mm, in the Littrow configuration and -1st order.</p>
<p><a href="https://i.sstatic.net/avIN9.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/avIN9.png" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2023-12-04T19:02:46.020Z
766nm is probably potassium.
ProfRob
CC BY-SA 4.0
2023-12-04T19:43:41.850Z
Potassium makes sense. Looks good.
Paolo Inverse
CC BY-SA 4.0
2023-12-04T18:01:24.060Z
2023-12-06T19:55:42.637Z
2023-12-06T19:55:42.637Z
Paolo Inverse
<p>I just built a DIY spectroscope using a CD and after making some tests, I noticed a really strong emission line located in the orange-yellowish zone of the fire spectrum (specifically, burning wood).</p>

<p>I think that the strong line could be actually sodium, but wouldn't that mean that wood contains a lot of sodium in order to see such a strong emission line?</p>

CC BY-SA 4.0
2019-11-21T02:59:28.960Z
It wa sSodium actually, sorry for reply late lol
Jotarata
CC BY-SA 4.0
2019-05-10T00:16:05.803Z
There's a related question on the Physics site about [orange colour in a gas flame](https://physics.stackexchange.com/q/441648/123208). There's some blackbody radiation, but the consensus is that the yellow lines are sodium. It doesn't take much salt to produce those lines.
PM 2Ring
CC BY-SA 4.0
2019-05-10T03:29:04.073Z
It's sodium. It's everywhere. This is why a lot of natural fires skew orange-yellow - it's the sodium pulling the color towards the yellow region. Even trace amounts will make that line, you don't need a ton of it. BTW, the line is a doublet, you can see it if your device has good spectral resolution.
Florin Andrei
CC BY-SA 4.0
2019-05-10T03:48:57.087Z
*Congratulations on building your own DIY spectroscope! I* propose you try to snap a photo through it and add it to your question, real data rocks! You might also see if adding a little salt or baking soda (sodium bicarbonate) to the fire enhances the yellow line. You also might consider moving your question to Chemistry, Physics, or Biology Stack Exchanges if people close your question here. If you can mention that you are truly *interested in looking at spectra of planets or stars or the Moon next*, that would keep your question on-topic here.
uhoh
CC BY-SA 4.0
2019-05-10T04:20:53.187Z
FWIW, you can probably also see a violet line from potassium. Traditionally, potassium hydroxide was made from wood ash. And sodium hydroxide from seaweed ash, which as you might guess has a lot of salt. ;)
PM 2Ring
CC BY-SA 4.0
2019-05-12T14:41:12.647Z
Throw some salt on the fire to confirm.
Wayfaring Stranger
CC BY-SA 4.0
2019-05-18T22:18:15.420Z
How I love this community!
Jotarata
CC BY-SA 4.0
2022-07-03T22:46:17.600Z
So it looked like the salted alcohol flame in my answer here: https://chemistry.stackexchange.com/a/164168/79678. ;-) Have an upvote!
Ed V
<spectroscopy><spectra>
Strong orange line in wood fire spectrum?
Jotarata
# Strong orange line in wood fire spectrum?

(Asked by: username_0 on 2019-05-09)

I just built a DIY spectroscope using a CD and after making some tests, I noticed a really strong emission line located in the orange-yellowish zone of the fire spectrum (specifically, burning wood).

I think that the strong line could be actually sodium, but wouldn't that mean that wood contains a lot of sodium in order to see such a strong emission line?

**Tags:** spectroscopy, spectra

> **Comments:**
> **username_1**: There's a related question on the Physics site about [orange colour in a gas flame](https://physics.stackexchange.com/q/441648/123208). There's some blackbody radiation, but the consensus is that the yellow lines are sodium. It doesn't take much salt to produce those lines.  
> **username_2**: It's sodium. It's everywhere. This is why a lot of natural fires skew orange-yellow - it's the sodium pulling the color towards the yellow region. Even trace amounts will make that line, you don't need a ton of it. BTW, the line is a doublet, you can see it if your device has good spectral resolution.  
> **username_3**: *Congratulations on building your own DIY spectroscope! I* propose you try to snap a photo through it and add it to your question, real data rocks! You might also see if adding a little salt or baking soda (sodium bicarbonate) to the fire enhances the yellow line. You also might consider moving your question to Chemistry, Physics, or Biology Stack Exchanges if people close your question here. If you can mention that you are truly *interested in looking at spectra of planets or stars or the Moon next*, that would keep your question on-topic here.  
> **username_1**: FWIW, you can probably also see a violet line from potassium. Traditionally, potassium hydroxide was made from wood ash. And sodium hydroxide from seaweed ash, which as you might guess has a lot of salt. ;)  
> **username_4**: Throw some salt on the fire to confirm.  
> **username_0**: How I love this community!  
> **username_0**: It wa sSodium actually, sorry for reply late lol  
> **username_5**: So it looked like the salted alcohol flame in my answer here: https://chemistry.stackexchange.com/a/164168/79678. ;-) Have an upvote!  

---

## 1 answers

### Answer by username_6 on 2023-12-04. Score: 5

Well,
I've pointed my spectrometer at my fireplace, and I can confirm the presence of a relatively strong sodium line(s). It just takes trace amounts of sodium to produce this signature, it cannot be mistaken.

I also see an emission band around 765~766nm, of unknown origin, though username_7 points out below that it's likely to be potassium.

Don't mind the dots, those are hot pixels, my spectrometer is using a 100um slit and requires long exposure times. The sensor is an inexpensive OV2640, spectral lines calibration is within <0.7nm but I'm still in the process of performing the spectral responsivity calibration. And it might still be slightly out of focus.

This instrument uses an actual transmissive grating, 500lines/mm, in the Littrow configuration and -1st order.

[![enter image description here](https://i.sstatic.net/avIN9.png)](https://i.sstatic.net/avIN9.png)

> **Comments:**
> **username_7**: 766nm is probably potassium.  
> **username_6**: Potassium makes sense. Looks good.  

---

