Dynamics of high <i>n</i> molecular Rydberg states with application to mass analyzed threshold ionization spectroscopy

Abstract

Studies are performed which measure the lifetime of very high lying molecular Rydberg states which play a central role in high resolution threshold ionization spectroscopy. The molecular systems investigated are styrene, phenol, and phenanthrene as well as the atomic iron system for comparison. It is shown that the lifetimes of the highest lying levels are determined not by intramolecular nonradiative processes but by intermolecular Rydberg–ion or Rydberg–Rydberg interactions. Under low fluence laser excitation, the highest lying Rydberg states are observed to have a lifetime greater than 25 μs but under high fluence the observed lifetime is ∼4 μs. The long Rydberg lifetimes are utilized to implement a simplified spectrometer for mass analyzed threshold ionization (MATI) spectroscopy.