Synchrotron radiation emitted from the UVSOR storage ring is monochromated by a grazing-incidence monochromator and introduced coaxially with the second harmonic of a mode-locked Ti:sapphire laser. Sample gases, N(2) and N(2)O, are photoionized into vibronically ground N(2)(+) with the fundamental light of the undulator radiation at 18.0 and 18.6 eV, respectively. Laser-induced fluorescence (LIF) excitation spectra of N(2)(+) from N(2) and N(2)O are measured in the laser wavelength region of the (B (2)Sigma(u)(+), v' = 0) <-- (X (2)Sigma(g)(+), v" = 0) transition at 389-392 nm. The LIF excitation spectra of N(2)(+) exhibit two maxima due to the P and R branches in which rotational bands are heavily overlapped. The rotational temperature is determined by simulating an LIF excitation spectrum by using the theoretical intensity distribution of rotation bands convoluted with the spectral width of the laser.

In northeast Thailand, the rapid expansion of rainfed paddy fields has decreased the stability of rice production. This paper describes a model that computes rice production on the basis of the hydrologic conditions of rainfed paddy fields on hill slopes. The model well expressed the hydrologic processes, rice yield, and production at the study site. We simulated rice production as uphill paddy plots are abandoned, increasing catchment area, under various rainfall conditions. The simulation showed that rice yield and stability increase as uphill plots are abandoned, although the total rice production decreases. Thus, the effect of catchment size on rice production in each plot was quantified. The model proved to be useful for analyzing rainfed rice production under various land and water conditions.

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A mode-locked Ti:sapphire laser is made to oscillate at the frequency of the UVSOR storage ring, 90.115 MHz, in a multi-bunch operation mode. The third harmonic of the laser is available in the wavelength range 243-280 nm. Synchrotron radiation from an undulator is monochromatized by a grazing-incidence monochromator and introduced coaxially with the laser. The temporal profile of the photon pulses is monitored in situ by a luminescing substance/photomultiplier combination. The delay timing between the laser and synchrotron radiation can be changed from 0 to 11 ns by adjusting an electronic module that provides phase-locked loop stabilization of the laser pulse. The reliability and feasibility of this laser-synchrotron radiation combination technique are demonstrated by applying pump-probe experiments to two physical systems. The first system is photodissociation of iodomethane (CHA) with a laser photon, followed by photoionization of I and CH3 fragments with synchrotron radiation. The second, two-photon ionization of He atoms, is studied as the prototype of a time-resolved experiment. The He + signal counts as a function of the laser-synchrotron radiation delay are found to be enhanced in a narrow time window, which can be interpreted in terms of a short lifetime of the resonant state, He*(ls2p ip), produced by primary synchrotron radiation excitation.

Using the parallel-plate-condenser method, we have measured gross ionization cross sections in fully stripped-ion ͑charge state qϭ2 -18) impact on rare gases and simple molecules (H 2 , N 2 , O 2 , and CO 2 ) at a fixed collision energy E of 6 MeV/amu. The observed cross sections have been found to depend weakly on the charge state q compared with the q 2 dependence, especially for highly charged projectiles and/or heavy target elements. Therefore, the Bethe-Born calculations tend to overestimate the gross ionization cross sections in multiply charged ion impact at the present collision energy. For a particular target, the gross ionization cross sections have been found to gather on a common curve irrespective of the projectile energy and charge state when the cross section divided by the charge state is plotted against the projectile energy per nucleon divided by the charge state, giving some credence to a scaling law based upon the classical trajectory Monte Carlo ͑CTMC͒ method. However, CTMC calculations tend to underestimate the ionization cross sections especially at the high-energy region of E/qϾ0.3 ͑MeV/amu͒. A scaling for the gross ionization cross sections of rare gases in fully stripped-ion impact is proposed.