I'm sure it's exactly like you'd guess, I forgot to make/choose an image until the very last second and so I found the first image on my computer that looked relatively unique. Come to think of it, I should have cited the creator. It was in a friend's PhD thesis and I'm 90% sure she made it herself. Her name is (now Dr.) Emma Van Burns. It's meant to illustrate plasmons in metal nanoparticles resonating with the electric field of light
And thank you for listening and your kind comment!