Abstract: The invention includes methods of making a fluorine doped soot particle. One method of the invention includes the steps of (1) delivering a silicon containing precursor to a first opening in a burner face; (2) delivering a source of oxygen to a second opening, wherein the second opening is spaced apart from the first opening such that the silicon precursor and oxygen source react to form a soot particle having a surface area of more than about 20 m2/g; and (3) delivering a fluorine precursor to a third opening, said third opening is spaced apart from the first opening. A second method of the invention includes the steps of (A) delivering a silicon containing precursor to a first opening in a burner face; (B) delivering a fluorine precursor to a second opening, wherein said second opening is spaced apart from said first opening; and (C) delivering a fuel to a third opening, said third opening is spaced apart from said first opening.