Types of Luminescence

[@natanabelian1901]

Amazing channel, took my interest of phys chem to another level!

[@PhysicalChemistry]

That's what I like to hear!

[@gowtham5168]

nice.much knowledge condensed in one video .. that keeps it engaging .

[@Bow503]

The writing backwards is impressive

[@PhysicalChemistry]

Not as impressive as you think: kzbin.info/www/bejne/j57Ze4mhrq-VgsU

[@sidewaysfcs0718]

Lanthanide compounds are usually phosphorescent because those are spin-forbidden transitions. The lifetime of those excited states are ~ 10^-3 s. Persistent luminescence ( minutes, hours) can actually be both fluorescence OR phosphorescence, the extremely long lifetimes are due to electron traps in point defects in lattices. Phosphorescence is NOT defined by lifetime, but by spin change.

[@PhysicalChemistry]

Good comments, thanks. The preceding two videos on fluorescence (kzbin.info/www/bejne/nnauaISfasufj7c) and phosphorescence (kzbin.info/www/bejne/jGSVlqtvmqh5fqs) -- both linked in the suggested videos on top right -- have more info about spin and timescales for those two phenomena.

[@NicholasLeeson]

What type of luminescence causes the aurora lights? Thanks

[@PhysicalChemistry]

Great question! This is collisionally excited emission. Particles from the solar wind (e.g. an electron) collide with atoms or molecules in the upper atmosphere (e.g. an oxygen atom), leaving them in an electronically excited state (e.g. ¹D). That excited atom or molecule then releases energy by emitting a photon (e.g. 557 nm). Different collisions produce different colors of auroral light

[@NicholasLeeson]

@@PhysicalChemistry Cool, thanks for your response. Do you know if it's all fluorescence, i.e. the lifetime of the excited electron is on the order 10ns; or are we dealing with phosphorescence, i.e. within 1us? Or is both, depending on which atom is being excited? Thanks again.

[@PhysicalChemistry]

@@NicholasLeeson It's slow, "forbidden" transitions, but it wouldn't be called phosphorescence because the source of the excitation energy is collisions with particles, not light

[@NicholasLeeson]

@@PhysicalChemistry Great, many thanks 😊

[@nicolenew1708]

INCREDIBLY COOL

[@alexandere9928]

What about electroluminescence? We use electricity to produce light

[@PhysicalChemistry]

Yes, definitely! That's more a common and practical phenomenon than some of the others on my list.

[@adabigeertac7364]

this video was really helpful.

[@PhysicalChemistry]

Great, glad you thought so

[@shorifahmed261]

Lovely ❤

[@PhysicalChemistry]

Very cool stuff, right?

[@Jasmera]

Cool!

[@PhysicalChemistry]

I agree!

[@abogeteddy1299]

Quite informative but You forgot about sonar luminescence .

[@PhysicalChemistry]

Yes, good point. Sonoluminescence is quite cool, too

[@pokercardsriver]

You forgot Sono luminescents