Three-State Laser

The population inversion needed for a laser can't be achieved with just two electronic states. But with three states, the system can be pumped up to an upper state, in order to maintain a population inversion relative to an intermediate state.

[@tanmaybakshi6828]

Thanks a lot for this! You're an excellent teacher!!!! Best of Luck to you....

[@PhysicalChemistry]

You're very welcome, I appreciate the kind words

[@bikashsahu4809]

Superb explanation 👌, hats off to u sir

[@PhysicalChemistry]

Thanks, I appreciate that

[@adithyan9263]

please upload more videos on lasers your videos are the only i understand 🥺🥺🥺

[@adithyan9263]

please upload more videos on lasers your videos are the only ones i understand 🥺🥺🥺

[@PhysicalChemistry]

I'm very glad the videos were useful for you. But you'll have to find another source -- hopefully a better one! -- to dive deeper, as I don't have any plans to do any more videos on lasers.

[@adithyan9263]

@@PhysicalChemistry ok🥺

[@mortezakhoshbin]

thanks dear dr stuart. I didnt find a lecture about bonds to ask this question there. but it makes me curious why some molecules have low degradation temperature although the bonds are the same as other more stable molecules. molecules like maleic anhydride composed of the c-c and c-o but are degraded in low temperature in comparision to other molecules.( i want to use it by other molecules in 280 degree of celsious but it degrades in low temperatures and i need to use it😔)

[@PhysicalChemistry]

Good question. I don't know the answer. I guess it could depend on a lot of things: whether the decomposition is taking place in the presence of something that it reacts with, or something that can act as a catalyst for the decomposition; whether the first decomposition products are more likely to end in a termination step or continue a chain reaction; etc.

[@mortezakhoshbin]

@@PhysicalChemistry Thanks alot. if we increase Temp with pure material and He atmosphere to exit oxygen we have molecules different degradation temprature yet. i was thinking it may be related to movement of molecules which damp the energy but as you said it can depend on alot of things. anyway thank you for helping🌹🌹🙏