Ion pair imaging spectroscopy:: CH3Cl → CH3++Cl-

Application of the imaging technique to study the photodissociation of molecules to ion pair products can be a powerful means of probing ion energetics and spectroscopy. This approach, analogous to photoelectron spectroscopy. has the advantage that it may be applied to systems for which stable neutral precursors may not exist. In this letter we describe the technique and show the first demonstration of the method: CH3Cl - CH3+ + Cl-. The results provide insight into the vibrational frequencies of the methyl cation and the ion pair dissociation dynamics of methyl chloride, and illustrate the advantages of the method. (C) 2001 Elsevier Science B.V. All rights reserved.