Role of ultrafast dissociation in the fragmentation of chlorinated methanes

Photon-induced fragmentation of a full set of chlorinated methanes (CH₃Cl, CH₂Cl₂, CHCl₃, CCl₄) has been investigated both experimentally and computationally. Using synchrotron radiation and electron-ion coincidence measurements, the dissociation processes were studied after chlorine 2p electron excitation. Experimental evidence for CH₃Cl and CH₂Cl₂ contains unique features suggesting that fast dissociation processes take place. By contrast, CHCl₃ and CCl₄ molecules do not contain the same features, hinting that they experience alternative mechanisms for dissociation and charge migration. Computational work indicates differing rates of charge movement after the core-excitation, which can be used to explain the differences observed experimentally.