Raman Analysis of Chemical Reactions Resulting from the Collision of Micrometer-Sized Particles

Abstract

The chemical reaction between two micrometer-sized particles has been studied with the use of Raman spectroscopy. Charged particles of Na₂CO₃ and (NH₄)₂SO₄ were generated with the use of a vibrating orifice aerosol generator fitted with an inductive charging plate. Two particles, one of each substance and of opposite polarity, were held apart by the dc electric field of an electrodynamic balance (EDB) and then brought together by manipulating the dc potential to permit Coloumbic forces to dominate. Raman spectra taken of the particle aggregate show that chemical reaction did not occur when dry particles were combined, but subsequent exposure of the aggregate to water vapor induced a chemical reaction that resulted in the formation of Na₂SO₄. The Raman data are presented, and the reaction mechanism and products are discussed.