@ 2:55 In my imagination, going for 1s to 2s the distance between the electrons is increased and thus the dipole is increased. Where am I going wrong here?
The best explanation sir.. Can you please tell me By using a Frack-Condon term and a Herzberg Teller term, pls show how the transition dipole moment can be written
Hey, this is a great video, thank you! What I still have difficulties with understanding is the "inducing" of a dipole when the light comes in. When I think about dipoles, I think about two charges separated by a distance which then generate the dipole. When I however go from a 1s to a 2s - or a 1s to a 2p - orbital, I "take" the electron and "put" it somewhere where it is now either distributed like it was before (1s -> 2s) or differently (1s -> 2p). However, it is still only one electron and I don't seem to see where this dipole comes into play and wheter it is always there or just "appears" during the transition. If someone could help that would be great.
Atoms and molecules are electrically neutral. So if the electron (or electron density) is somewhere, there is also always a positive charge density somewhere else in the atom. So there is an electrical dipole. The incoming oscillating electromagnetic wave makes the electron oscillate in resonance. This oscillating electron is an oscillating dipole. The transition from 1s to 2s is forbidden, because the electron density in the 1s and the 2s state is located in the center of the atom in both cases. So the electron density cannot oscillate between the 1s electron-distribution and the 2s electron-distribution. The distance that the electron oscillated would be zero, so it does not oscillate. Correct me if I'm wrong.
@@Gabriel-bt3nd The dipole moment is the magnitude of the negative charge multiplied by the distance between the charges. Here the two charges will be the positive charge inside the nucleus and the negative charge of the electrons. If the electrons make a transition to the 2s the magnitude remains the same but the distance changes. The same is the case with a transition to 2p. So the dipole moment in both cases should not be zero (as distance changes). But it becomes zero because of the integration which includes the direction dependence and becomes zero due to the equal probability of electron in 2s in all directions. But in 2p also, it is not distributed in all the directions but the electron can reside in 2 lobes in the opposite direction, So will that also not make the total dipole moment equal to 0.
JK87 like he said, you can't go from 1s to 2s. You can only go to 2p. So, basically they made this into a rule and called the rule : dipole selection rule. What the rule says is you can only go : +1 L or - 1 L
This blew my mind. My spectroscopy professor never made the link between the transition dipole moment and selection rules this explicitly!
Or were you sleeping when he did?
Lol
almost completing my degree and this just clicked in my head. God bless you
sheesh same here
i love you. the best thing i have seen this year.
Thank you so much sir, I'm searching for this transition dipole moment.
Very concisely explained, excellent job!
Excellent Video... Thank you...
good explaination
@ 2:55 In my imagination, going for 1s to 2s the distance between the electrons is increased and thus the dipole is increased. Where am I going wrong here?
The best explanation sir.. Can you please tell me By using a Frack-Condon term and a Herzberg Teller term, pls show how the transition dipole moment can be written
Thank you very much.
So simply explained! 😦
very nicely explained . Thanku sir
Great explanation. Thanks!
thank you!
Great explanation! Subscribed
Perfect video
Hey, this is a great video, thank you!
What I still have difficulties with understanding is the "inducing" of a dipole when the light comes in. When I think about dipoles, I think about two charges separated by a distance which then generate the dipole. When I however go from a 1s to a 2s - or a 1s to a 2p - orbital, I "take" the electron and "put" it somewhere where it is now either distributed like it was before (1s -> 2s) or differently (1s -> 2p). However, it is still only one electron and I don't seem to see where this dipole comes into play and wheter it is always there or just "appears" during the transition. If someone could help that would be great.
Exactly! I have the same doubt.
Atoms and molecules are electrically neutral. So if the electron (or electron density) is somewhere, there is also always a positive charge density somewhere else in the atom. So there is an electrical dipole. The incoming oscillating electromagnetic wave makes the electron oscillate in resonance. This oscillating electron is an oscillating dipole.
The transition from 1s to 2s is forbidden, because the electron density in the 1s and the 2s state is located in the center of the atom in both cases. So the electron density cannot oscillate between the 1s electron-distribution and the 2s electron-distribution. The distance that the electron oscillated would be zero, so it does not oscillate.
Correct me if I'm wrong.
@@Gabriel-bt3nd The dipole moment is the magnitude of the negative charge multiplied by the distance between the charges. Here the two charges will be the positive charge inside the nucleus and the negative charge of the electrons. If the electrons make a transition to the 2s the magnitude remains the same but the distance changes. The same is the case with a transition to 2p. So the dipole moment in both cases should not be zero (as distance changes). But it becomes zero because of the integration which includes the direction dependence and becomes zero due to the equal probability of electron in 2s in all directions. But in 2p also, it is not distributed in all the directions but the electron can reside in 2 lobes in the opposite direction, So will that also not make the total dipole moment equal to 0.
With the mathematical equation of the TDM in mind, the explanation looks nice. But a dipole has two poles. I've never seen a dipole in this video.
Thank You so much!
Can you please define: What are dipole selection rules. And how is this connected to the transition dipole moment?
JK87 like he said, you can't go from 1s to 2s. You can only go to 2p. So, basically they made this into a rule and called the rule : dipole selection rule. What the rule says is you can only go : +1 L or - 1 L
JK87 L is just called orbital angular momentum. Where the orbital angular momentum (L ) of S orbital is 0 , p is 1, d is 2 and so on
JK87 so you can only go from s to a p. Since it is +1L . You can't go to d, it is +2L . +2L is not allowed
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