A chemical dispensing apparatus for providing a chlorine vapor to a reaction chamber is disclosed. The chemical dispensing apparatus may include: a chemical storage vessel configured for storing a chlorine-containing chemical species, a reservoir vessel in fluid communication with the chemical storage vessel, the reservoir vessel configured for converting the chlorine-containing chemical species to the chlorine vapor, and a reaction chamber in fluid communication with the reservoir vessel. Methods for dispensing a chlorine vapor to a reaction chamber are also disclosed.