Using Time of Flight Mass Spectrometry to Determine Temperature

In support of measurements of rate coefficients and other atomic and molecular parameters for astronomy and astrophysics, we are developing a method of obtaining and analyzing time of flight spectra (TOFS). This is analogous to obtaining temperatures from profiles of optical emission lines. Using a cylindrical RF ion trap, ion clouds were generated by bombarding H$_{2}$ and N$_{2}$ gas at nano-torr pressures with electrons having roughly 100 eV of kinetic energy. The ion clouds were ejected from the trap by applying voltage pulses to the trap end caps, and detected using an electron multiplier. The voltage, rise time, and RF phase of the ejection pulse were varied to obtain either the best charge-to-mass resolution or to obtain the best information on the energy distribution of stored ions. The TOFS produced under these conditions were modeled and simulated using Sim-Ion 7.0 ion optics software. The experiment and simulation data are compared and information pertaining to the kinetic energies of the ions in the generated ion cloud is presented.