Dear all, I was doing cleaning of naphthalene through zone refinement. After it is finished impurities from the naphthalene concentrate completely in one place of the ampule (lower part). I was interested to see which type of impurities are collected and did a spectroscopy measurement. Couple of samples were measured (NS1 - NS5) which you can see on figure I attached. There are clear absorption peaks on the NS3 absorption line. My question is, is anyone familiar with elements, molecules or any other particles that would absorb light in this way? To me it seems that 622 nm, 595 nm, 572 nm, 549 nm and 526 nm are actually the same transition only different vibronic levels. Therefore I would say that these belong to the same particle. Maybe even 686 nm and 655 nm could belong there although they have a little bit higher spacing. For 512 nm, 463 nm and 445 nm I have no idea how to relate them. I searched these wavelengths, but unfortunately I could not find any candidate that would fit. Another constraint. Since these are spectra obtained from naphthalene I would suppose that impurities must be related to the process of naphthalene synthesis. That is only my assumption. I would be very grateful if someone could help me about this. Best.