Measurement of Ion–Molecule Reaction Rate Constants Using Ion Cyclotron Resonance

The theory of ion cyclotron resonance line shapes has been developed for the case where the ion does not suffer any collisions with the neutral gas molecules. Experimental results are in very good agreement with the theoretical line shape. Expressions have been derived for the single resonance signal intensities of both primary and secondary ions at low pressure. Ion–molecule reaction rate constants obtained for the following reactions were $${\mathrm{CH}}_4^{+}+{\mathrm{CH}}_4\to {\mathrm{CH}}_5^{+}+{\mathrm{CH}}_3{\text{, 9.5\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−10}}{\mathrm{cm}}^3/\mathrm{mole}·\sec ,$$ $${\mathrm{CH}}_2{\mathrm{D}}_2^{+}+{\mathrm{CH}}_2{\mathrm{D}}_2\to {\mathrm{CH}}_3{\mathrm{D}}_2+{\mathrm{CHD}}_2{\text{, 5.1\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−10}},$$ $${\mathrm{CH}}_2{\mathrm{D}}_2^{+}+{\mathrm{CH}}_2{\mathrm{D}}_2\to {\mathrm{CH}}_2{\mathrm{D}}_3^{+}+{\mathrm{CH}}_2\mathrm{D}{\text{, 4.1\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−10}},$$ $${\mathrm{C}}_2{\mathrm{H}}_2^{+}+{\mathrm{C}}_2{\mathrm{H}}_2\to {\mathrm{C}}_4{\mathrm{H}}_2+{\mathrm{H}}_2{\text{, 3.9\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−10}},$$ $${\mathrm{C}}_2{\mathrm{H}}_2+{\mathrm{C}}_2{\mathrm{H}}_2\to {\mathrm{C}}_4{\mathrm{H}}_3^{+}+\mathrm{H}{\text{, 8.3\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−10}},$$ and are in good agreement with rate constants obtained by other techniques.