Laser spectroscopy and optical pumping of alkali atoms in superfluid helium

In this paper, our recent works on the alkali atoms in superfluid helim (HeII) are reported. At first we mentions the laser-sputtering method for implantation, which is simple but is very efficient to produce various kinds of neutral atoms and molecules in HeII. Secondly, we report on the laser spectroscopy of alkali atoms in HeII. Optical excitation and emission spectra are found to be roughly explained by a spherical atomic bubble model, but the spectra corresponding to the D₂ lines indicate the quadrupole oscillation of the bubble shape. Optical pumping by a circularly polarized laser beam is found to produce perfect polarization, for both electron and nuclear spins. Using the rf-optical double resonance techniques, the magnetic and hyperfine resonances are observed. It is discussed also about the phenomena which have observed in the experiments done so far but have not been fully explained.     

Core-level photoemission of the Si(1 1 1)– -Ag surface using synchrotron radiation

The evolution of Si 2p core-level photoemission during a structural conversion from the Si (1 1 1)– -Ag to the Si(1 1 1)– -Ag superstructures induced by Ag adatoms adsorption at 140 K was studied using synchrotron radiation. The component from the top-layer Si-trimer atoms on the former surface was found to split into two components in the latter surface. The result is discussed in terms of a relaxation in some of the Si trimers induced by Ag adatoms sitting on the nearby Ag triangles of the -Ag substrate. The intensity ratio between the split components is a key to exclude some structure models proposed so far for the phases.     

Color confining parton model for heavy quarkonium decay

We present a gluon jet model for the heavy quarkonium decay incorporating the color neutralization mechanism. Postulating that final hadrons are produced from the color singlet quark-antiquark pair originated each from different gluons, we formulate the production mechanism of hadrons from gluons explicitly. The fragmentation function thus obtained can describe the hadron production not only in the fragmentation region but also in the central one owing to the usage of the Sudakov variables. The result of the average charged multiplicity from Υ(9.46) is in reasonable agreement with the data, in contrast to the naive estimates. Furthermore, the inclusive momentum and multiplicity distributions are discussed.     

X-ray and IR studies on crystal and molecular structure of 4-nitro-2,6-diphenylphenol. Stereochemistry of bifurcated OH⋯π hydrogen bonds

The crystals of the title compound contain both intra- and inter-molecular OH?π hydrogen bonds (the first example of bifurcated OH?π bonds), the stereochemistry of which has been elucidated by an X-ray structure analysis; this bifurcated bond is also supported by the observation based on the IR spectrum of the crystals.     

Kinetics of the phosphorescent triplet states of tetracyanobenzene complexes as studied by microwave induced delayed phosphorescence

Using microwave induced delayed phosphorescence techniques we determined the populating and depopulating rate constants for the individual spin-sublevels of the phosphorescent states of tetracyanobenzene (TCNB) and its charge-transfer complexes with benzene and hexamethylbenzene (HMB) in n-hexane at 1.25 K. It was shown that the non-radiative decay process from the shortest lifetime sublevel is most responsible for the previously observed shortening in the phosphorescence lifetime of the TCNBHMB complex.