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Ion dip spectroscopy of cold molecules and ions. Progress report

Technical Report ·
DOI:https://doi.org/10.2172/674623· OSTI ID:674623
During the past year, the main emphasis in this research program has been on multiphoton ionization spectroscopy of aromatic clusters. This is being pursued in addition to continuing work in areas of ion dip spectroscopy and ion fragmentation spectroscopy. The program has the overall objective of developing improved ultrasensitive molecular detection methods based on multiphoton laser spectroscopy. Photoionization techniques are employed due to their extreme sensitivity combined with mass selectivity. The combination of these two features has led to the current capability to study molecular clusters of specific sizes with high spectral resolution. Clusters are formed in abundance in a supersonic expansion, where they are excited and ionized by an ultraviolet laser beam. The studies reported here are principally based on simple resonant excitation of clusters, followed by one-photon ionization. For the naphthalene clusters, a single laser wavelength suffices for both excitation steps. Additional investigations have been carried out to measure excited state cluster ionization spectra and cluster ion fragmentation spectra. Results from these measurements are not yet sufficiently advanced to report in detail, however the preliminary data support the importance of recently proposed new fundamental ionization mechanisms in clusters. This brief report summarizes results described in more detail in the preprint titled: Resonant two-photon ionization spectroscopy of naphthalene clusters and the preprint titled: Resonance interactions in naphthalene clusters. It also briefly describes preliminary undisclosed results of current investigations.
Research Organization:
Aerospace Corp., El Segundo, CA (United States)
Sponsoring Organization:
USDOE Office of Energy Research, Washington, DC (United States)
DOE Contract Number:
FG03-86ER60391
OSTI ID:
674623
Report Number(s):
DOE/ER/60391--T7; ON: DE99000260
Country of Publication:
United States
Language:
English