Hajime Katô

Pathogenicity, Mating Ability and DNA Restriction Fragment Length Polymorphisms of Pyricularia Populations Isolated from Gramineae, Bambusideae and Zingiberaceae Plants

Eighty-five Pyricularia isolates were collected from 29 host species of Gramineae, Bambusideae and Zingiberaceae plants sampled in Brazil, Uganda, Ivory Coast, India, Nepal, China, Indonesia and Japan. These isolates were compared on the basis of pathogenicity, mating ability and restriction fragment length polymorphisms with single-copy DNA probes. Based on the pathogenicity to eight differential gramineous plants, these isolates were classified into seven pathotypes: finger millet type, foxtail millet type, common millet type, rice type, crabgrass type, Italian ryegrass/ weeping lovegrass type, and non-cereal/grass type. Genetic variation among these isolates was assessed by RFLP analysis with two restriction enzymes and nine single-copy DNA probes isolated from a finger millet strain. An UPGMA dendrogram based on the RFLPs revealed that the 85 isolates could be classified into seven major groups. Isolates from cereal crops (finger millet, foxtail millet, common millet, wheat and rice) and a grass, Brachiaria plantaginea, were clustered into a single group. They were further divided into six subgroups corresponding to the pathotypes. Among cereal crop isolates only an isolate from pearl millet was located into a different group. The remaining isolates were clustered into five groups designated as the crabgrass group, the buffelgrass and jungle rice group, the rice cutgrass, knotroot bristlegrass and Setaria tomentosa group, the bamboo and bamboo grass group and the Zingiber mioga group. The isolates from cereal crops were generally capable of mating with finger millet strains and constituted a closed mating compatibility group. These results suggested that the isolates from cereal crops form a single group with a common ancestor although they are pathogenic to taxonomically diverse plants. A combined analysis of the pathogenicity and genetic similarity suggested that the transmission of M. grisea isolates occurs in natural agroecosystems between finger millet and Eleusine africana, goosegrass or Bambusa arundinacea, between foxtail millet and green bristlegrass, and between rice and tall fescue, Italian ryegrass, sweet vernalgrass, reed canarygrass or Oryza longistaminata.

Laser‐induced fluorescence of NaK and the dissociated atoms

Intensity distribution of both bound–bound and bound–continuum transitions of the NaK d 3Π1→a 3Σ+ fluorescence has been analyzed by calculating Franck–Condon factors for the transitions. The potential curves of the d 3Π1 state and the dissociative continuum of the a 3Σ+ state have been estimated by comparing the observed and the calculated intensities, and the variation of the transition dipole moment with internuclear distance has been evaluated. Besides molecular fluorescence, the fluorescence of the D lines of Na and K atoms were observed. The absolute and the relative intensities of the atomic D1 and D2 lines have been found to be different between the Na and K atoms. The effects of a foreign gas on atomic D lines and their dependence on a frequency of excitation are studied, and the mechanism responsible for the atomic emission is examined.

Perturbations of the A 1Σ+u and b 3Πu states of Na2 and the effects on the transition intensity and the line splitting

Doppler‐free polarization spectra of the A 1Σ+u (v=8, J=0–15) and b 3Π0u (v=14, J=0–15) states were observed. By analyzing the energy shifts, the spin–orbit interaction between the A 1Σ+u (v=8) and b 3Π0u (v=14) states was studied. The magnitudes of the hyperfine splittings were different in corresponding lines of the two states. In addition to the energy shifts, the line intensities and the line shapes were found to change remarkably near the perturbation. These are useful to study the mixing of the perturbing states.

Laser induced fluorescence, energy transfer and dissociation of Cs2

Laser induced fluorescences of Cs2 excited by the Ar+ laser lines have been studied. A series of lines with vibrational progression and the successive diffuse bands in the region down to 16 200 cm−1 were found to be polarized and identified as the resonance fluorescence. The diffuse fluctuation band with a maximum of intensity at 16 400 cm−1 consists of several bands at regular interval and it was independent on the line of excitation. By applying the theory on the role of kinetic energy in the Franck–Condon principle proposed by Mulliken, the band was identified as a transition from the internuclear distance of maximum kinetic energy in the vibrational level of the excited state E 1πu. All the other fluorescence bands of low frequency were observed to be depolarized completely, and the intensities increased when a foreign gas was added. These bands were identified as the fluorescence from the states which were populated by collision‐induced transitions from the E state. Atomic fluorescence 6p 2P3/2→6s 2S...

Doppler-free optical–optical double resonance polarization spectroscopy of the 39K85Rb1 1Π and 2 1Π states

High resolution spectra of the 1  1 Π(v ′ =13–69,J ′ )←X  1 Σ + (v ″ ,J ″ ) and 2  1 Π(v ′ =0–13,J ′ )←X  1 Σ + (v ″ ,J ″ ) transitions of the 39 K 85 Rb molecule have been measured with the technique of Doppler-free optical–optical double resonance polarizationspectroscopy (OODRPS). Molecular constants of the 1  1 Π(v=13–69) and 2  1 Π(v=0–13) levels have been determined, and potential energy curves constructed by the RKR method. The RKR potential of the 1  1 Π state was found to have a distortion at outer wall, which originates from an avoided crossing of two 1 Π states. The perturbations between the 1  1 Π(v 1 ,J) and 2  1 Π(v 2 ,J) levels were found from the energy shifts of the rotational levels. The magnitude of the nonadiabaticinteraction between the 1  1 Π(v 1 =54) and 2  1 Π(v 2 =9) levels, 〈1  1 Π(v 1 =54)|T N |2  1 Π(v 2 =9)〉, was evaluated to be 2.2 cm−1 by a least squares fitting to the energy shifts of the 1  1 Π(v 1 =54,J=20–33) levels. The line intensities were observed to change dramatically around the maximum energy shift. These intensity anomalies are interpreted as an interference effect, which occurs when two interacting levels have comparable transition moments. A remarkable line broadening was observed for the transitions to the 1  1 Π(v⩾63) levels, and it was identified as originating from the predissociation to K (4s 2 S 1/2 )+ Rb (5p 2 P 1/2 ) atoms. The dissociation energies of the X  1 Σ + , 1  1 Π, and 2  1 Π states have been determined to be 4217.4±0.8, 2021.5±0.8, and 1050.0±0.8 cm−1, respectively.

Doppler‐free high resolution laser spectroscopy of the Cs2 D 1Σ+u state and the predissociation

A Doppler‐free polarization spectrum of the D 1Σ+u(v’,J’)–X 1Σ+g(v‘,J‘) transition has been observed, and the molecular constants of the D 1Σ+u state were determined. A remarkable variation of the vibrational spacing ΔGv with v’, and large deviations of ΔGv from the fitted ΔGv curve for v’≳35 were analyzed. The potential curve of the perturbing state, which was identified as the bound (2)3Πu state, was estimated. By using an experimental setup where a collimated cesium beam is crossed at right angles by the laser beam, we measured the excitation spectra by monitoring separately the molecular fluorescence and the D2 or D1 atomic emission. We found that a predissociation of the D 1Σ+u state occurred for v’≳20, and the probability of predissociation increased with v’. The measured v’ and J’ dependence of the linewidth Γ showed a significant increase for v’≳25. The predissociation of the D 1Σ+u state is caused by a combination of spin–orbit interaction between the D 1Σ+u(v’J’) and (2)3Π0u(e vJ’) levels, and t...

Hyperfine structure of the NaK c 3Σ+ state and the effects of perturbation

Scanning the frequency of a single‐mode dye laser crossed with a molecular beam of NaK, we have measured the excitation spectrum by monitoring selectively the fluorescence intensity of transition to the a 3Σ+ state. The B 1Π(v=8) and c 3Σ+(v=22) levels are perturbed around J=5 and the c 3Σ+(v=22) and b 3Π(v≊62) levels are perturbed around J=24. The transition lines to the perturbed levels are fully resolved. The hyperfine splitting, which is induced by the coupling with the nuclear spins of the Na and K atoms, is observed for levels of the c 3Σ+ state and the perturbed states. The magnitude of the hyperfine splitting, the line intensity, and the energy shift are analyzed, and their relation with the perturbation is studied. The ratio of electron spin densities at the sodium and potassium atoms in the c 3Σ+ state is estimated to be 0.71:0.15 from the magnitudes of hyperfine splitting.

Laser‐induced fluorescence of the NaRb molecule

Several series of laser‐induced fluorescence lines of the heteronuclear alkali dimer NaRb have been observed when a mixture of sodium and rubidium is irradiated by the He–Ne, Ar+, or Kr+ laser line. The spectroscopic constants of the X 1Σ+ ground state have been determined and the potential energy curve has been calculated by the RKR method. RKR potential curves for the excited B 1Π and D 1Π have been determined by comparing the observed and calculated intensity distributions as well as the transition energies. The dependence of the transition dipole moment upon the internuclear distance has been estimated. The fluorescence of the D lines of Na and Rb atoms and a less intense fluorescence, which is assigned as a transition to the a 3Σ+ state in NaRb, have been observed. From the measured vibrational spacing, which can be followed close to the dissociation limit, the dissociation energy De of the a 3Σ+ state is determined to be 568±5 cm−1.

High resolution laser spectroscopy of the B 1Π−X 1∑+ transition of 23Na39K, and the perturbation between the B 1Π and c 3∑+ states

The Doppler‐free laser polarization spectrum of the B1Π −X1∑+ transition of 23Na39K was measured, and the molecular constants of the B1Π state of v=0∼16 were determined. The perturbation between the B1Π(v=8) and the c3∑+(v=22) levels at small J were studied in detail. By comparing the observed line intensities of the B1Π(v=16, J=14) −X1∑+(v‘=0∼50, J=13 and 15) transition with the calculated Franck–Condon factors, the dependence of the transition dipole moment on the internuclear distance was determined. Absolute vibrational numbering of the c3∑+ state was done by comparing the calculated Franck–Condon factors with the observed line intensities of the c3∑+ −a3∑+ transition.

Optical–optical double resonance polarization spectroscopy of the B 1Π state of 39K85Rb

High resolution spectra of the B 1Π←X 1Σ+ transition of the 39K85Rb molecule have been measured with the technique of Doppler‐free optical–optical double resonance polarization spectroscopy. Molecular constants of the B 1Π(v′=0−12) levels are determined, and the RKR potential is calculated. A number of irregularities in the energies of B 1Π state levels and intensity anomalies are observed. The energy shifts of the e and f levels of the B 1Π state are studied, and the perturbations between the B 1Π and 3Σ+ states and between the B 1Π and 3Π1 states are identified. Several transitions to the 3Π1 and 3Σ+ states are also observed, and the molecular constants of the 3Π1 and 3Σ+ states are evaluated. The single rovibrational level B 1Π(v′=2, J′=41) is selectively excited by a single frequency laser chopped by an electro‐optical modulator, and the decay time of the resulting fluorescence is measured at various pressures. From the Stern–Volmer plot, the radiative lifetime and the collisional cross section of the...