Studies with sputter-generated molecular anions

Studies pertaining to the formation, stability and physicochemical properties of molecular anions are of tremendous interest. Among various experimental techniques, the sputtering process is well known for production of wide range of molecular anions. The formation of molecular anions at surface undergoing sputtering are observed to follow trends similar to either Electron affinity (EA) or Bond energy (BDE) values. In addition, the availability of intact molecules at the site of sputter-selvedge has seemed to be crucial and decisive point in their anion formation probabilities. These facts are studied for different interfaces; i.e. gas-solid, atomic and compound solids at Secondary Ion Mass Spectrometry (SIMS) level. It is shown that, even the available sputtering model for atomic anions fail to explain the probable mechanism underlying the sputter formation of molecular anions, the presented approach allow us to correctly rationalize the observed yields patterns of molecular anions, qualitatively. The ion intensities were observed to follow exponential scaling with EA values for intact molecules already available on the sputter-surface and the bond energy dependence for anions formed by combination of atoms from two different origins. The gas-phase existence of new superhalogen anions of metal fluorides and metal oxides using Ab initio, SIMS and AMS (Accelerator Mass Spectrometry) methods will be discussed in detail.