Photoionization studies with molecular beams
A molecular beam photoionization apparatus which combines the advantages of both the molecular beam method with photoionization mass spectrometry has been designed and constructed for carrying out some unique photoionization experiments. Rotational cooling during the supersonic expansion has resulted in high resolution photoionization efficiency curves for NO, ICl, C/sub 2/H/sub 2/ and CH/sub 3/I. The analysis of these spectra has yielded ionization potentials for these molecules to an accuracy of +- 3 MeV. Detailed autoionization structures were also resolved. This allows the investigation of the selection rules for autoionization, and the identification of the Rydberg series which converge to the excited states of the molecular ions. The degree of relaxation for thermally populated excited states has been examined using NO and ICl as examples. As a result of adiabatic cooling, a small percentage of dimers is also formed during the expansion. The photoionization efficiency curves for (NO)/sub 2/, ArICl, Ar/sub 2/, Kr/sub 2/ and Xe/sub 2/ have been obtained near the thresholds. Using the known dissociation energies of the (NO)/sub 2/, Ar/sub 2/, Kr/sub 2/ and Xe/sub 2/ van der Waals molecules, the corresponding dissociation energies for NO-NO/sup +/, Ar/sub 2//sup +/, Kr/sub 2//sup +/, and Xe/sub 2//sup +/ have been determined. The ionization mechanisms for this class of molecules are examined and discussed.
- Research Organization:
- California Univ., Berkeley (USA). Lawrence Berkeley Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 7327888
- Report Number(s):
- LBL-5439
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ACETYLENE
ALKYNES
ARGON
ARGON CHLORIDES
ARGON COMPOUNDS
ARGON IODIDES
AUTOIONIZATION
BEAMS
CHALCOGENIDES
CHLORIDES
CHLORINE COMPOUNDS
DISSOCIATION
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUID FLOW
HALIDES
HALOGEN COMPOUNDS
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROCARBONS
IODIDES
IODINATED ALIPHATIC HYDROCARBONS
IODINE CHLORIDES
IODINE COMPOUNDS
IONIZATION
KRYPTON
METHYL IODIDE
MOLECULAR BEAMS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOIONIZATION
RARE GAS COMPOUNDS
RARE GASES
RELAXATION
ROTATIONAL STATES
SUPERSONIC FLOW
XENON