DYNAMICS OF HIGH N-MOLECULAR RYDBERG STATES WITH APPLICATION TO MASS-ANALYZED THRESHOLD IONIZATION SPECTROSCOPY

Studies are performed which measure the lifetime of very high lying mo lecular Rydberg states which play a central role in high resolution th reshold ionization spectroscopy. The molecular systems investigated ar e styrene, phenol, and phenanthrene as well as the atomic iron system for comparison. It is shown that the lifetimes of the highest lying le vels are determined not by intramolecular nonradiative processes but b y intermolecular Rydberg-ion or Rydberg-Rydberg interactions. Under lo w fluence laser excitation, the highest lying Rydberg states are obser ved to have a lifetime greater than 25 mus but under high fluence the observed lifetime is approximately 4 mus. The long Rydberg lifetimes a re utilized to implement a simplified spectrometer for mass analyzed t hreshold ionization (MATI) spectroscopy.