Jun-ichi Murakami

Multiphoton ionization spectra of benzene, fluorobenzene, and chlorobenzene resonant with S0–S1 transitions by use of nozzle beam method

Multiphoton ionization technique combined with nozzle beam method was applied to the observation of two‐photon absorption spectra of benzene, fluorobenzene, and chlorobenzene in S0–S1 valence shell excitations. Strong two‐photon activity of ν14 (b2u or b2) vibration throughout these molecules was established. Details of the multiphoton ionization spectrum of chlorobenzene which was observed for the first time will be given. It was concluded that the two‐photon resonant four‐photon ionization spectra obtained in the present work reflect correct two‐photon absorption cross sections. The vibrational temperature of a lower frequency vibration was found to decrease preferentially in an expanded low temperature nozzle beam.

The multiphoton ionization spectrum of toluene in a supersonic free jet: internal rotation of the methyl group

Abstract The S 1 ← S o electronic transitions of toluene involving also some internal rotational levels were observed for the first time in the multiphoton ionization spectrum in a supersonic jet. A large population in several low-lying internal rotational levels and a strong coupling between electronic motion and the internal rotation are suggested.

Electronic absorption spectra of biphenyl as studied by multiphoton ionization–supersonic beam technique

The vibrational structure of biphenyl is studied by observing the multiphoton ionization spectra due to radiation from a dye (coumarin 540) laser.(AIP)

Low lying 1A2u(σ,π*) and 1E2g(π,π*) states of benzene as suggested by Raman intensities

The Raman spectra of benzene, substituted benzenes, and charge transfer complexes between benzene and halogens were observed. The great preresonance intensity enhancement of the out‐of‐plane ν10(e1g) Raman line of benzene and its intensification upon the complex formation strongly suggest the existence of the low lying 1A2u(σ,π*) state of benzene. On the other hand, the preresonance Raman effect of the overtone of the ν14(b2u) vibration of benzene and the strong appearance of Raman and infrared inactive fundamentals ν16(e2u) and ν17(e2u) of benzene upon the complex formation can be explained by assuming the low lying 1E2g(π,π*) states. It is qualitatively concluded that the perturbation imposed on benzene in the direction perpendicular to the molecular plane induces the intensity enhancements of the out‐of‐plane vibrations, while the perturbation parallel to the molecular plane contributes greatly to the Raman intensities of the in‐plane modes.

Ion dip spectra toluene and aniline in a supersonic free jet

Abstract The ion dip spectra toluene and aniline were measured using a supersonic free jet. It was demonstrated that an ion dip spectrum gives a ratio of the transition probablity from a ground state to a resonant intermediate state and that from the intermediate state to the ionization continuum.

Spatial and velocity distributions of desorbing product carbon dioxide over a reconstructed platinum (110)(1 × 2) surface

Abstract The spatial and velocity distributions of desorbing products were measured in the CO oxidation on Pt(110)(1 × 2) by a cross-correlation time-of-flight technique combined with angle-resolved thermal desorption. The analysis indicates that. with increasing CO coverage, the reaction site is extended from inclined terraces of the reconstructed surface to the non-reconstructed plane.

Positive ion fractions of recoiled A1 and O from O-adsorbed Al surfaces by low-energy ion bombardment

Abstract Oxygen-adsorbed polycrystalline Al surfaces were bombarded by a pulsed low-energy (500 eV) Ar+ or Ne+ beam. Time-of-flight spectra for neutrals plus positive ions or neutrals only were measured to study the dependence of the positive ion fractions of recoiled particles on O adsorption. It was found that an increase in O concentration on an Al surface enhances a recoil Al+ fraction for the Ar+ bombardment and a recoil O+ fraction for the Ne+ bombardment. The increase in the Al+ fraction is attributed mainly to the change in the charge state of Al upon formation of the Al-O bond, while the increase in the recoil O+ fraction is attributed to the change in electron transfer rates between the surfaces and the incident Ne or recoiled O. The result shows that the recoil O+ fraction for low-energy Ne+ bombardment is a useful probe for a change in electron transfer rates to and from metal surfaces upon O adsorption.