Ion time-of-flight lineshapes are found to be drastically altered by the process of tunneling field ionization in the case of near-threshold photoionization. The delay-time distributions observed correspond directly to the times for tunneling through the field-ionization barrier. Using this effect, field ionization rates can be precisely measured over a wide dynamic range by high-resolution mass spectrometry. Results for threshold ionization of the Al atom in fields of 5-500 V/cm and mean decay time of 0.02 to 20 μs are presented to illustrate the decay profiles and threshold shifts observed. The latter values can be explained using the concept of the classical barrier to field ionization.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry