Emission spectroscopy of an acetylene flame

In summary, the student was studying the emission spectrum of an acetylene flame and noticed that the intensity increase as the amount of oxygen in the fuel mix increased. Around about 610-620 nm there's a dip and around 700 nm there's a very prominent dip that grows more significant the more oxygen that's released into the mix. There are some serious dangers in doing this experiment, so if not already fitted, I suggest installing spark and lighting back prevention devices.
  • #1
Matthew Adams
1
0
Hey there folks!

This is my first post so please be gentle... ;-)

One of my students has been studying the emission spectrum of an acetylene flame. A gas mixture from both an acetylene cannister & an oxygen canister is fed out to a nozzle, a flame is ignited and we study the emission spectrum...

For a minimum of oxygen, we get the following spectrum:
O3aDJmQ.png


So far, so good. The peaks are as far as I understand from CH & C2 in the combustion of acetylene. The flame has a nice blue colour to it.

The fun begins when we start to increase the amount of oxygen in the fuel mix:
dXK93IS.jpg


So basically, the more oxygen that is let in, the higher the measured intensity and the more the spectrum takes on the form of a black body spectrum. Around about 610-620 nm there's a slight dip and around 700 nm there's a very prominent dip that grows more significant the more oxygen that's released into the mix. As you might expect, the flame also grows more orange/yellow and more sooty, the more oxygen that's fed into the mix.

So my question is basically: what's going on? Not too sure about the dip around 610-620nm, but I think the dip at 700nm is from O2 (that or water).

If anyone can shine some light on this and give some explanation for why the intensity increases the way it does for increased oxygen, what's causing those dips and why the spectrum takes on the form of BB radiation for increasing oxygen content in the fuel, I'd be more than grateful.
 
Physics news on Phys.org
  • #2
Matthew Adams said:
As you might expect, the flame also grows more orange/yellow and more sooty, the more oxygen that's fed into the mix.

That is not what I would expect to happen . Increasing Oxygen flow relative to a fixed Acetylene flow just causes flame to burn cleaner and more intensely until such time as flame becomes unstable and either blows out or you get lighting back into the burner tube and supply hoses .

Possibilities are that :

Acetylene is getting carbonised inside the hot tip zone of the burner tube .

Metal from the burner tube is being vaporised .

Lighting back is severe and bits of the seal rings and supply hoses are burning .

Please note that there are some serious dangers in doing this experiment . If not already fitted I suggest that you install spark and lighting back prevention devices before proceeding further .
 

Related to Emission spectroscopy of an acetylene flame

1. What is emission spectroscopy of an acetylene flame?

Emission spectroscopy of an acetylene flame is a technique used to analyze the elemental composition of a sample by measuring the light emitted from an acetylene flame. This method is based on the principle that each element has a unique emission spectrum, allowing for the identification and quantification of elements present in the sample.

2. How does emission spectroscopy of an acetylene flame work?

In this technique, a sample is introduced into a flame of acetylene gas, which is then heated to high temperatures. The heat causes the atoms in the sample to become excited, and as they return to their ground state, they emit light at specific wavelengths. This light is then analyzed using a spectrometer to determine the elemental composition of the sample.

3. What are the advantages of using an acetylene flame for emission spectroscopy?

Acetylene flames have a high temperature and a reducing environment, which helps to reduce any interference from contaminants in the sample. Additionally, the flame has a low background emission, allowing for better detection of the emitted light from the sample elements.

4. What are the limitations of emission spectroscopy of an acetylene flame?

One limitation of this technique is that it cannot distinguish between different isotopes of the same element. Additionally, it may not be suitable for samples that contain elements with low excitation energies or samples with very high or low concentrations of the elements of interest.

5. What are the applications of emission spectroscopy of an acetylene flame?

Emission spectroscopy of an acetylene flame has a wide range of applications in various fields such as environmental analysis, material science, and forensic science. It is commonly used to analyze the composition of metals, minerals, and biological samples. It can also be used for quality control and process monitoring in industries such as pharmaceuticals and petrochemicals.

Similar threads

I Continuous Spectrum and Energy levels of Electrons (Energy Bands)
    • Quantum Physics
Replies
7
Views
1K
Understanding molecular absorption of light (UV-Vis spectroscopy)
    • Atomic and Condensed Matter
Replies
3
Views
4K
Flame test and black (or gray) body
    • Other Physics Topics
Replies
9
Views
3K
What is the structure of black holes?
    • Other Physics Topics
Replies
2
Views
2K
New Materials (new china industry),could this be the next bill gates($$$) industry?
    • Materials and Chemical Engineering
Replies
4
Views
8K

Hot Threads

Recent Insights

Back
Top