Sub-Doppler high-resolution excitation spectroscopy of the S1 ← S0 transition of dibenzofuran

Rotationally resolved ultrahigh-resolution fluorescence excitation spectra of the S₁ ← S₀ transition of dibenzofuran have been observed using the technique of crossing a collimated molecular beam and the single-mode UV laser beam. 3291 rotational lines of the band and 3047 rotational lines of the band have been assigned. The band has been found to be a b-type transition, in which the transition moment is along the twofold symmetry axis of this molecule, and only the ΔK_a = ± 1 transitions were observed. The excited state is identified to be the S₁¹A₁(ππ^∗) state. In contrast with this, the band has been found to be an a-type transition in which the transition moment is along the long axis in plane. It indicates that the intensity of this vibronic band arises from vibronic coupling with the S₂¹B₂(ππ^∗) state. We determined the accurate rotational constants and the molecule have been shown to be planar both in the ground and excited states.     

Infrared reflection absorption study of carbon monoxide adsorption on Pd/Cu(1 1 1)

Pd-Cu bimetallic surfaces formed through a vacuum-deposition of Pd on Cu(1 1 1) have been discussed on the basis of carbon monoxide (CO) adsorption: CO is used as a surface probe and infrared reflection absorption (IRRAS) spectra are recorded for the CO-adsorbed surfaces. Low energy electron diffraction (LEED) patterns for the bimetallic surfaces reveal six-fold symmetry even after the deposition of 0.6 nm. The lattice spacings estimated by the separations of reflection high-energy electron diffraction (RHEED) streaks increase with increasing Pd thickness. Room-temperature CO exposures to the bimetallic surfaces formed by the Pd depositions less than 0.3 nm thickness generate the IRRAS bands due to the three-fold-hollow-, bridge- and linear-bonded CO to Pd atoms. In particular, on the 0.1 nm-thick Pd surface, the linear-bonded CO band becomes apparent at an earlier stage of the exposure. In contrast, the bridge-bonded CO band dominates the IRRAS spectra for CO adsorption on the 0.6 nm-thick Pd surface, at which the lattice spacing corresponds to that of Pd(1 1 1). A 90 K-CO exposure to the 0.1 nm-thick Pd surface leads to the IRRAS bands caused not only by CO-Pd but also by CO-Cu, while the Cu-related band is almost absent from the spectra for the 0.3 nm-thick Pd surface. The results clearly reveal that local atomic structures of the outermost bimetallic surface can be discussed by the IRRAS spectra for the probe molecule.     

Measurement of time-dependent CP-violating asymmetries in B0 --> K(s)0K(s)0K(s)0 decay

We present a measurement of CP-violation parameters in the B0 --> K(s)0K(s)0K(s)0 decay based on a sample of 275 x 10(6) BB pairs collected at the upsilon(4S) resonance with the Belle detector at the KEKB energy-asymmetric e+e- collider. One neutral B meson is fully reconstructed in the decay B0 --> K(s)0K(s)0K(s)0, and the flavor of the accompanying B meson is identified from its decay products. CP-violation parameters are obtained from the asymmetry in the distributions of the proper-time interval between the two B decays: S = +1.26 +/- 0.68(stat) +/- 0.20(syst) and [symbol: see text] = +0.54 +/- 0.34(stat) +/- 0.09(syst).     

Observation of the D1(2420)-->Dpi + pi- decays

We report on the first observation of D0/1(2420)-->D0pi- pi+ and D+/1(2420-->D+ pi- pi+ decays (where the contribution from the dominant known D1-->D*pi decay mode is excluded) in the B- -->D0/1pi-) and (-)B0-->D+/1pi- decays, respectively. The observation is based on 15.2 x 10(7) B(-)B events collected with the Belle detector at the KEKB collider. We also set 90% confidence level upper limits for the branching fractions of the four following decays: B- -->D0/1pi-, D01-->D(*0)pi- pi+, (-)B0-->D+/1pi-, D+/1-->D(*+) pi- pi+, B- -->D(*0)2(2460)pi-, D(*0)2 -->D(*0) pi- pi+, (-)B0-->D(*+)2(2460)pi-, D(*+)2-->D(*+)pi- pi+.     

Observation of a near-threshold omegaJ/psi mass enhancement in exclusive B-->KomegaJ/psi decays

We report the observation of a near-threshold enhancement in the omegaJ/psi invariant mass distribution for exclusive B-->KomegaJ/psi decays. The results are obtained from a 253 fb(-1) data sample that contains 275 x 10(6) BB pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e(+)e(-) collider. The statistical significance of the omegaJ/psi mass enhancement is estimated to be greater than 8sigma.     

Search for D0-D0 mixing in D0 --> K+ pi(-) decays and measurement of the doubly-Cabibbo-suppressed decay rate

We have searched for mixing in the D(0)-D (0) system by measuring the decay-time distribution of D(0) --> K(+) pi(-) decays. The analysis uses 90 fb(-1) of data collected by the Belle detector at the KEKB e(+) e(-) collider. We fit the decay-time distribution for the mixing parameters x' and y' and also for the parameter R(D), which is the ratio of the rate for the doubly-Cabibbo-suppressed decay D(0)--> K+ pi(-) to that for the Cabibbo-favored decay D(0)--> K-pi(+). We do these fits both assuming CP conservation and allowing for CP violation. We use a frequentist method to obtain a 95% C.L. region in the x'(2) - y' plane. Assuming no mixing, we measure R(D) = (0.381 +/- 0.017(+0.008)(-0.016))%.     

Determination of the structure of {31}ne by a fully microscopic framework

We perform the first quantitative analysis of the reaction cross sections of {28-32}Ne by {12}C at 240 MeV/nucleon, using the double-folding model with the Melbourne g matrix and the deformed projectile density calculated by antisymmetrized molecular dynamics. To describe the tail of the last neutron of {31}Ne, we adopt the resonating group method combined with antisymmetrized molecular dynamics. The theoretical prediction excellently reproduces the measured cross sections of {28-32}Ne with no adjustable parameters. The ground state properties of {31}Ne, i.e., strong deformation and a halo structure with spin parity 3/2{-}, are clarified.