Knowledge Bank

Instrumentation which allows the infrared spectroscopic observation of mass-selected, matrix-isolated ions has been developed. Mass-selected cations are generated using a modified quadrupole mass spectrometer and subsequently trapped in neon or argon matrices. Preliminary experiments with $CF3+$, generated from $CF3X$ (X = H, Cl, Br), have shown that sufficient quantities can be isolated to permit detection of the antisymmetric stretch $(\nu 3)$. The cations are observed without the concurrent deposition of anions. Negatively charged particles are, however, observed upon warring of the substrate, indicating that the matrix is maintaining approximate electrical neutrality by an as yet unknown mechanism. Some of the small amount of neutral precursor which diffuses onto the matrix may undergo electron attachment. Absorptions consistent with previous assignments to $CF3Cl-$ in $argon1$ have been observed, but similar features have not yet been detected in neon.