At the bottom of the test tube is liquid phenylacetylene and on top, we have liquified chlorine. When a UV laser is pointed at both, a cool reaction takes place and tetrachloroethylbenzene is formed (black). (Video by ChemicalForce)

At the bottom of the test tube is liquid phenylacetylene and on top, we have liquified chlorine. When a UV laser is pointed at both, a cool reaction takes place and tetrachloroethylbenzene is formed (black). (Video by ChemicalForce)