Answer: Electrons.
Step-by-step explanation: To initiate the light dependent reactions, electrons must be excited. When light is absorbed by the chlorophyll molecule, the electrons get excited and moves from a ground state to excited state.
The energy is converted in the form of heat when the electrons returns from the excited state to ground state.
In case an electron acceptor is there, the excited electron moves to the acceptor. The loss of electron from the substance makes it positive and there is negative charge on the acceptor,this creates a photo induced separation.