High-Pressure Study of Ion-Molecule Reactions in the Mixture of Carbon Tetrafluoride and Argon

Charge-exchange ion-molecule reactions of $Ar^+$ ions with $CF_4$ have been studied in the pressure range 1.33-39.99 Pa. A quadrupole mass spectrometer with a high-pressure ion source has been used for measuring gaseous ion-molecule reactions in the mixture of 1% $CF_4$ and 99% Ar. The fractional abundance $I_i//\sum I_i$ of the observed $CF_3^+$, $CF_2^+$ and argon ions has been determined as a function of the gas mixture pressure (at the values of the repeller electrode potentials $V_{R}$ ranging from 2 to 10 V)

Mass-Spectrometric Investigations of Silver Clusters

We report results of experimental studies on the silver clusters formation in laser desorption and matrix assisted laser desorption. Time-of-flight mass spectrometer was used to control process itself. Firstly, we investigated dependence of silver salts of variety chemical nature on formation of silver clusters. The most prominent was usage of organic silver salts (silver trifluoroacetate and silver benzoate). The biggest species obtained was $Ag_{45}^{+}$ (silver benzoate). Secondly, we examined influence of organic matrix (2,5-dihydroxybenzoic acid) on formation efficiency of silver clusters in matrix assisted laser desorption. In all cases we observed increase of silver clusters size