Molecular beam photoionization studies of molecules and their van der Waals clusters

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1982

OSTI ID:5903238

Ono, Y

A new photoionization apparatus incorporating a supersonic molecular beam, a quadrupole mass spectrometer and a 3-m vacuum ultraviolet monochromator has been used to study the nitric oxide, carbon disulfide, carbonyl sulfide and acetylene molecules along with their van der Waals clusters. Using a wavelength resolution of 0.14 A (FWHM), photoionization efficiency curves were obtained for NO, CS/sub 2/, OCS, and C/sub 2/H/sub 2/ in the respective threshold regions and ionization energy determinations accurate to within 3 MeV were made. The autoionization structures resolved have led to new interpretations and assignments to Rydberg levels. Photoionization efficiency data for the clusters were obtained under lower resolution, typically 1.4 A (FWHM) and led to binding energy determinations of the cluster ions. Other thermochemical values were deducted from fragment appearance energies and sharp rises in ionization efficiencies. From the (CS/sub 2/)/sub 2/ fragment curves, relative reaction probabilities for the formation of the various product channels as a function of the Rydberg level n were determined for CS/sub 2/(V,n).CS/sub 2/ and the branching ratios were measured for the reaction CS/sub 2/(V,n) + CS/sub 2/. The shifts observed in the autoionization peaks of the triatomic molecules CS/sub 2/ and OCS due to clustering was investigated and a model is proposed which accounts for these characteristics. Ionization of the acetylene dimer and trimer resulted in clusters which could rearrange to form ions of a more stable configuration.

• OSTI ID: 5903238
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
640301 -- Atomic
Molecular & Chemical Physics-- Beams & their Reactions
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACETYLENE
ALKYNES
BEAMS
CARBON COMPOUNDS
CARBON OXYSULFIDE
CARBON SULFIDES
CHALCOGENIDES
ELECTROMAGNETIC RADIATION
HYDROCARBONS
IONIZATION
MOLECULAR BEAMS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOIONIZATION
RADIATIONS
SULFIDES
SULFUR COMPOUNDS
ULTRAVIOLET RADIATION
VAN DER WAALS FORCES