Absorption spectrum in chlorophyll

AI Thread Summary
The discussion centers on the broad peaks observed in the absorption spectrum of chlorophyll, questioning why they are not sharper given the principle that photon wavelengths must match the energy difference between atomic states. It is noted that chlorophyll's complexity, being composed of many atoms, contributes to this broadening. Additionally, the conversation highlights the significant number of photons required for photosynthesis, specifically in the Calvin cycle, where over 15 photons are needed to produce a single sugar molecule. The efficiency of the RuBisCO enzyme in capturing these photons is also questioned, particularly how many photons must interact with it in a short time frame. The complexity of chlorophyll and the photosynthetic process underscores the intricate nature of energy absorption in plants.
annnna
Messages
1
Reaction score
0
I have a question.

We claim that the wavelength of a photon must exactly match the difference between the states of an atom or molecule. Then why are the peaks in the absorption spectrum of chlorophyll so broad? Shouldn’t they be very sharp?
 
Physics news on Phys.org
annnna said:
I have a question.

We claim that the wavelength of a photon must exactly match the difference between the states of an atom or molecule. Then why are the peaks in the absorption spectrum of chlorophyll so broad? Shouldn’t they be very sharp?
No, because it's a complex molecule, made of many tens of atoms:
http://en.wikipedia.org/wiki/Chlorophyll
 
lightarrow said:
No, because it's a complex molecule, made of many tens of atoms:
http://en.wikipedia.org/wiki/Chlorophyll
How come it takes so many photons to make a single sugar molecule via the C3 (Calvin) cycle photosynthesis? The heat of oxidation (to 6CO2 and 6H2O) of C6H12O6 is about 29 eV per molecule. Peaks in the absorption spectrum are less than ~2 eV per photon, so this implies over 15 photons per molecule. In fact studying the RuBisCO cycle implies ~4 photons per CH2O group, or ~24 photons per simple sugar molecule (monosaccharide). How many said photons have to hit the RuBisCO molecule in a millisecond to make the sugar molecule?

Bob S
 
Last edited:

Thread 'Need help understanding particle physics and quantum physics'

So I know that electrons are fundamental, there's no 'material' that makes them up, it's like talking about a colour itself rather than a car or a flower. Now protons and neutrons and quarks and whatever other stuff is there fundamentally, I want someone to kind of teach me these, I have a lot of questions that books might not give the answer in the way I understand. Thanks
View full post »

Similar threads

I Only certain emission lines show up in absorption spectrum
Replies
4
Views
2K
I Gases: Not Required to Be Blackbodies
Replies
19
Views
17K
B Line absorption spectrum and stars
Replies
9
Views
2K
I Why is the EM spectrum contiguous instead of gapped
Replies
16
Views
2K
B What type of spectrum is a rainbow?
Replies
22
Views
6K
I Line Spectra and low density gases
Replies
5
Views
2K
A Physical explanation of time-correlation function and spectrum
Replies
3
Views
2K
Atmospheric CO2 absorption - actual quantification?
Replies
42
Views
18K
How can we explain continuous absorption / emission?
Replies
1
Views
2K
B Sun's peak wavelengths and chlorophyll's green colour
Replies
27
Views
2K

Hot Threads

Recent Insights

Back
Top