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We measured the saturated absorption spectra of Kr I at 811.51 nm by using a titanium sapphire ring laser. Saturated absorption spectroscopy (SAS) is a simple and high-resolution spectroscopic technique. The hyperfine structure and isotope shift of the resonance lines were investigated by analyzing the 5s[3/2]2 → 5p[5/2]3 transition observed in the saturated absorption spectra of Kr I. The King plot method was used to analyze the isotope shift composed of normal shift, specific shift, and volume shift. Based on this analysis, the unperturbed position of 83Kr relative to that of 84Kr was estimated to be 16.4 MHz. Furthermore, the magnetic dipole hyperfine constant A and electric quadrupole hyperfine constant B in the 5p[5/2]3 state were calculated to be A = −103.79(6) and B = −439.8(17) MHz, and those in the 5s[3/2]2 state were A = −243.88(8) and B = −454.4(13) MHz, respectively. [ABSTRACT FROM AUTHOR]

Reflectron-type time-of-flight mass spectrometry was applied to the time-resolved component analysis of deep oscillation magnetron sputtering (DOMS), which has been developed as a technique of modulated pulsed magnetron sputtering. In the present study, the DOMS of a Ti target was performed under an Ar gas atmosphere by using a DOMS-specific control waveform consisting of 25 current and/or power pulses. The time evolution of the formation of ionized species (Ar+, Ar2+, Ti+, and Ti2+) after the application of the first discharge pulse was observed at the position corresponding to the deposition region. This study revealed that the plasma build-up process from non-metallic plasma to metallic plasma takes approximately two micropulses (around 100 μs from ignition) in DOMS discharge. In addition, we have found the possibility of studying sputtering processes, such as the rarefaction, and refilling processes of Ar as a function of pulse number through DOMS research. [ABSTRACT FROM AUTHOR]

The photodissociation spectra of size-selected Ca+(H2O)n (n=1–6) ions are examined in the wavelength region from 330 to 1440 nm by monitoring the total yield of the fragment ions. The absorption bands exhibit redshifts as large as ∼16 000 cm-1 with respect to the 2P–2S resonance line of the free Ca+ ion and are explained by the shift of this transition as a result of hydration. The converging trend in the spectral shifts at n∼6 is discussed in relation to the filling of the first solvation shell for Ca+ undergoing the sdσ hybridization. We also discuss the possible contribution of charge-transfer character in the observed transitions in conjunction with our recent results on the photoelectron spectra of Na-(NH3)n. The mass spectra of the fragment ions show the existence of two dissociation channels: The evaporation of water molecules and the dehydrogenation reaction to produce the hydrated CaOH+ ions. The evaporation process is the dominant decay channel for n=1, while the reaction is the only one for n≥3. The former process is found to take place from the higher vibrational levels in the ground state being populated through the fast internal conversion induced by the presence of the low-lying 2D-type states. As for n=1, the reaction takes place only in an excited state which has the Ca+p orbital aligned on the intermolecular axis. The state-specific reaction for n=1 is explained in terms of charge-transfer interaction between the Ca+ ion and the water molecule. On the other hand, the reactivity for the larger clusters drastically increases with increasing cluster size. These reaction features are discussed in comparison with those for Mg+(H2O)n reported previously. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Photoionization thresholds for silicon clusters in the size range Si2 to Si200 have been examined by laser photoionization with detection by reflectron time-of-flight mass spectrometry. Stimulated Raman scattering light of narrow bandwidth 193 nm radiation was used as the ionization light source down to 146 nm. A characteristic size dependence of ionization potentials (IPs) was found for clusters smaller than 22 atoms, featuring major maxima at n=10 and 20. We also found a large gap in IPs between n=20 and 22. This gap was ascribed to the structural transition of neutral clusters in analogy with that found recently for small silicon cluster ions. The IPs for larger clusters with n=100–200 silicon atoms were found to be 5.0–5.17 eV, which are lower than the ionization energy but still higher than the work function of bulk Si(111) surface. This difference was discussed with relation to the nature of surface states for both phases. [ABSTRACT FROM AUTHOR]