This project will follow up work that established and experimentally verified a theory of strong resonance multiphoton coupling in diatomic molecules. The goals of the project are to use this phenomenon in molecular hydrogen ions to populate vibrationally-bound excited states that have never before been studied. This effort will likely lead to the creation of population inversions on transitions around 9 eV. The project will also involve a study of the dynamics of strong-field ionization to evaluate an important assumption that is typically made in strong field physics, namely, the least bound electron is ionized by the strong laser field. It has been difficult to determine which electron is removed, or equivalently, in which electronic state the molecular ion is left. The final state of molecular ions produced by strong laser fields will be determined by measuring their unique vibrational motion's signature through pump-probe spectroscopy. This vibrational motion can also reveal information about electronic states of molecules that have not been studied before.
Beyond the specific field of study, strong multiphoton coupling in molecular systems may lead to a novel and possibly efficient way of producing amplification in the vacuum ultraviolet spectral region and it may also lead to a new source of metastable hydrogen atoms. After many years of research, basic questions about the behavior of diatomic molecules in strong laser fields remain, especially the extent of vibrational and electronic excitation. Until these questions are answered applications such as quantum tomography and high-harmonic generation will not be precisely understood. While addressing these questions, the project will determine new information about the electronic structure of molecular ions, which is important for physical chemistry. Finally, these experiments require state-of-the-art laser systems, giving students hands on experience building and refining the latest laser and optical technologies, preparing them for a variety of research-based academic or high-tech career paths.
