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We report on the selective-area growth and characterization of wurtzite (WZ) InP/AlGaP core–multishell nanowires. Quantum well (QW) structures were fabricated in AlGaP multishells by changing the alloy composition. Transmission electron microscopy revealed that the AlGaP multishells were grown with a WZ structure on the side of the WZ InP core. The lattice constants of the WZ InP core and WZ AlGaP shell were determined by X-ray diffraction. Cathodoluminescence studies showed that the WZ AlGaP QW with an Al composition of 20% exhibited green emissions at 2.37 eV. These results open the possibility of fabricating green light-emitting diodes using WZ AlGaP-based materials. [ABSTRACT FROM AUTHOR]

Purpose: Dimethyl α‐ketoglutarate (dm‐α‐KG) promotes in vitro development to blastocysts of C57BL/6J X C3He F1 mouse zygotes cultured in medium lacking pyruvate. Here, we examined the effects of pyruvate and dm‐α‐KG on in vitro development to blastocysts of ICR mouse zygotes and their post‐implantation developmental ability. Methods: Zygotes were cultured in medium with pyruvate at 0‐0.2 mmol/L in the presence or absence of 1 mmol/L dm‐α‐KG for 96 hours and evaluated for blastocyst formation rates. The resultant blastocysts were non‐surgically transferred to surrogates and evaluated for birth rates. Results: In medium lacking pyruvate, zygotes could not develop beyond the two‐cell stage, in the presence or absence of dm‐α‐KG. However, the blastocyst formation rate in medium with 0.01 mmol/L pyruvate (12%) was markedly increased with addition of dm‐α‐KG (49%). Around 80% of embryos developed to blastocysts in medium with 0.2 mmol/L pyruvate, in the presence or absence of dm‐α‐KG. Importantly, birth rate was markedly improved by treatment with 0.2 mmol/L pyruvate and dm‐αKG (31.0%), compared with those with pyruvate treatment alone (16.3%). Conclusions: Pyruvate and dm‐α‐KG synergistically work during in vitro culture to markedly improve the blastocyst formation rate and post‐implantation developmental ability of the resultant blastocysts in ICR mice. [ABSTRACT FROM AUTHOR]

We grew AlInP on two types of GaN substrate in order to transfer the wurtzite (WZ) structure to grown layers. An AlInP epitaxial layer grown on GaN with high-density stacking faults was obtained. X-ray diffraction and Raman scattering analyses indicate that the dominant crystal structure of the AlInP layer grown on GaN was WZ. Cathode luminescence measurements at 35 K revealed strong green emissions from the WZ AlInP layer, suggesting an energy band gap change from indirect to direct. These results demonstrate the potential of WZ AlInP as a new candidate for high-efficiency green emission material. [ABSTRACT FROM AUTHOR]

Investigates the performance of Beta-alumina crystals as the monochromator crystal in synchrotron radiation sources in the photon energy region below 1.5 keV. Disadvantages of beryl crystals; Reflectivity of the Beta-alumina crystal; Measurements of the output spectra.

Objectives: To investigate the relationship between periprocedural myocardial injury (PMI) and plaque characteristics detected by multidetector computed tomography (MDCT) and cardiac magnetic resonance imaging (CMR). Materials and methods: This observational retrospective study, between July 2012 and October 2019, included chronic coronary syndrome patients undergoing elective percutaneous coronary intervention (PCI) after MDCT and CMR. High-intensity plaque (HIP) on non-contrast T1-weighted imaging was defined as a coronary plaque-to-myocardium signal intensity ratio of ≥ 1.4. High-risk plaque (HRP) in MDCT displayed ≥ 2 features: positive remodeling, low-attenuation plaque, spotty calcification, and napkin-ring sign. PMI was defined as an increase in cardiac troponin T levels > 5 times the upper normal limit at 24 h after PCI. Results: Ninety-five target lesions in 76 patients (mean age ± standard deviation, 67 years ± 9; 62 males [82%]) were included. Twenty-one patients (24 lesions) were assigned to the PMI group, while 55 patients (71 lesions) to the non-PMI group. Presence of HRP characteristics on MDCT and HIP on CMR was significantly higher in the PMI group. Multivariate logistic regression analysis showed that HRP in MDCT and HIP in CMR were significant independent predictors of PMI. Target lesions with HRP on MDCT and HIP on CMR were significantly more likely to develop PMI. In 141 plaques with ≥ 50% stenosis (76 patients), patients with PMI had significantly more frequent HRP in MDCT and HIP in CMR in target and non-target lesions. Conclusions: MDCT and CMR can play an important role in the detection of high-risk lesions for PMI following elective PCI. Key Points: • Multivariate logistic regression analysis showed that high-risk plaque on MDCT and high-intensity plaque on MRI were significant independent predictors of periprocedural myocardial injury (PMI). • Target lesions with high-risk plaque on MDCT and high-intensity plaque on CMR were significantly more likely to develop PMI. • In 141 plaques with ≥ 50% stenosis, patients with PMI were significantly more likely to have high-risk plaques on MDCT and high-intensity plaque on CMR in target and non-target lesions. [ABSTRACT FROM AUTHOR]

X-ray absorption spectra (XAS) of the lowest excited singlet, triplet, and ground states (S 1 , T 1 , S 0 -XAS) of benzoic acid and methyl benzoate in the O 1s region were calculated. Resonant core transition to a hole at the highest occupied molecular orbital (HOMO) created by valence excitation was predicted about 3 eV below the lowest peak of S 0 -XAS but with very weak intensity. A strong peak of the T 1 -XAS well separated from S 0 -XAS peaks is found for both molecules so that identification of the core-excitations from the T 1 and selective excitation of the T 1 become possible. Bond dynamics of oxygen-containing bonds in the potential energy surface of valence and core doubly excited states are estimated by using molecular dynamics simulation. Enhancement in known state-selective dissociation and new type of state selectiteve dissociation are predicted for the core excitations from valence excited state. [ABSTRACT FROM AUTHOR]

Dissociation of free methyl-formate (MF), HC(O)OCH3, and its clusters (MF)n, (HC(O)OCH3)n, induced by core-level excitation was studied near the oxygen K edge by time-of-flight fragment-mass spectroscopy. Besides the protonated clusters, (MF)nH+ with n≤15, we identified the production for another series of (MF)mCH3OH2+ with m≤14 as well as methyl-oxonium ion, CH3OH2+, characteristic of hydrogen transfer reactions in the cationic clusters. Here, specifically labeled methyl-formate-d (MFD), DC(O)OCH3 was also used to examine the core-excited dissociation mechanisms. Deuterium-labeled experiments indicated that MFD+ with low internal energies, partially generated after the core excitation, produces CH3OD+ via a site-specific deuterium transfer from the α carbonyl in the molecular cation and that CH3OD2+ can be formed via the successive transfer of another deuterium from the neighbor molecule in the clusters. The deuteron (proton) transfer was also found to take place preferentially from the α carbonyl of the neighbor molecule for the production of deuteronated (MFD)nD+, (protonated (MF)nH+), clusters. The minimal energy requirement paths were examined for dimer (MF)2+ cation to support the present dissociation mechanisms of core-excited (MF)n clusters using ab initio molecular-orbital calculations. [ABSTRACT FROM AUTHOR]

Vibrationally resolved spectra have been obtained for the lowest-lying cationic states X 2B1, A 2A1, and B 2B2 of the water molecule reached after participator resonant Auger decay of core-excited states. The angular distribution has been measured of the first four vibrational components of the X state in the photon energy regions including the O 1s→4a1 and the O 1s→2b2 core excitations, and for different portions of the vibrational envelope of the B state in the photon energy region including the O 1s→2b2 core excitation. For the X state, a large relative spread in β values of the different vibrational components is observed across both resonances. For the B state, a very different trend is observed for the high binding energy side and the low binding energy side of the related spectral feature as a function of photon energy. A theoretical method based on the scattering K matrix has been used to calculate both the photoabsorption spectrum and the β values, by taking both interference between direct and resonant photoemission and vibrational/lifetime interference into account. The numerical results show qualitative agreement with the trends detected in the experimental values and explain the conspicuous variations of the β values primarily in terms of coupling between direct and resonant photoemission by interaction terms of different sign for different final vibrational states. [ABSTRACT FROM AUTHOR]

BACKGROUND: Coronary plaques with positive remodeling (PR) and low-attenuation plaques (LAP) by computed tomography angiography (CTA) might be associated with plaque vulnerability. The purpose of this study was to assess the relation between coronary plaques with PR and LAP by CTA and fibrous cap thickness measured by optical coherence tomography (OCT). METHODS: We used CTA and OCT to assess 102 coronary plaques in patients with coronary artery disease (unstable angina pectoris, n=24; stable angina pectoris, n=78). Plaque characteristics were divided into three groups: 2-feature-positive plaques (PR and LAP; n=32), 1-feature-positive plaques (PR or LAP; n=20), and 2-feature-negative plaques (neither PR nor LAP; n=50). PR was defined as remodeling index (RI) of >1.05 and LAP was defined as CT density value <50HU. RESULTS: There were significant differences between the three plaque groups with respect to fibrous cap thickness measured by OCT: 76±24μm in 2-feature-positive plaques, 154±51μm in 1-feature-positive plaques, and 192±49μm in 2-feature-negative plaques (P<0.001). The RI (1.21±0.06, 1.14±0.05, P=0.011) and the presence of thin cap fibroatheroma (TCFA) (<70-μm thickness) (75%, 15%, P=0.001) were significantly higher in UAP than in SAP patients with 2-feature-positive plaques, whereas fibrous cap thickness (68.9±24.1, 92.1±21.9μm, P<0.001) was lower in the UAP patients. In UAP patients, the presence of ring-like enhancement showed higher accuracy of 88% for detection of TCFA. CONCLUSIONS: Coronary PR and LAP by CTA were associated with the degree of fibrous cap thickness measured by OCT. CTA can non-invasively provide promising information on plaque vulnerability by identifying coronary plaque with PR and LAP, especially ring-like enhancement. [ABSTRACT FROM AUTHOR]

Abstract: Background: The prophylactic benefit of statins in reducing the incidence of contrast-induced acute kidney injury (CI-AKI) has been investigated in several studies with conflicting results. We sought to investigate whether statin pretreatment prevents CI-AKI in coronary artery disease (CAD) patients undergoing percutaneous coronary intervention (PCI). Methods: A total of 2198 CAD patients who underwent PCI, except for those undergoing dialysis or who died within 7days after angioplasty, were analyzed from the ICAS (Ibaraki Cardiovascular Assessment Study) multicenter registry. Analyzed subjects were divided into 2 groups according to statin pretreatment: statin pretreatment (n=839) and non-statin pretreatment (n=1359). Selection bias of statin pretreatment was adjusted by propensity score-matching method: pretreatment statin (n=565) and non-statin pretreatment (n=565). CI-AKI was defined as an increase in serum creatinine of ≥25% or 0.5mg/dl from baseline within 1week of contrast medium exposure. Results: A total of 192 (8.7%) patients developed CI-AKI. No significant differences were observed in baseline patient characteristics between the statin and non-statin pretreatment groups after propensity score matching. In the propensity score-matched groups, the incidence of CI-AKI was significantly lower in patients with statin pretreatment than in those without statin pretreatment (3.5% vs.10.6%, odds ratio [OR]: 0.31, 95% confidence interval [CI]: 0.18–0.52, P <0.001). Multivariate logistic regression analysis showed that statin pretreatment remained an independent negative predictor of CI-AKI (OR: 0.31, 95% CI: 0.18–0.53, P <0.001) among propensity score-matched subjects. Conclusions: Statin pretreatment was associated with a significant decrease in the risk of CI-AKI in CAD patients undergoing PCI in the ICAS Registry. [Copyright &y& Elsevier]

Abstract: Time-of-flight mass spectra have been measured for inner-shell ionization of ethanol molecules, its clusters, and methanol clusters at the oxygen K-edge regions. Only in the case of the ethanol clusters, a fairly intense signal corresponding to H3O+ has been observed. The measurements for ethanol-d 1 (C2H5OD) suggest that at least one H atom in the H3O+ ion originates from the C2H5 group of neighbouring ethanol. It is proposed that in addition to the O–H⋯OH type hydrogen bonding in the ethanol clusters, the H in the C2H5 group and OH interact with each other. [Copyright &y& Elsevier]

Abstract: Dissociation of free acetonitrile-d3 molecule, CD3CN induced by core level excitation was studied near the nitrogen K-edge by time-of-flight fragment mass spectroscopy. A variety of atomic and molecular fragment cations such as D+, CD n +, C2D n +, and CD n CN+ were detected using the effusive CD3CN beam. Photoelectron–photoion–photoion coincidence technique was applied to analyse the dissociation mechanisms and dynamics of doubly charged CD3CN2+ following the N(1s–π *) excitation. The charge separation mechanisms of core-excited CD3CN were discussed in connection with Auger final state distributions. [Copyright &y& Elsevier]

Abstract: Dissociation of nitrous oxide clusters (N2O) n , induced by core level excitation near the nitrogen K-edge was studied by time-of-flight (TOF) fragment mass spectroscopy. Besides the cluster ions (N2O) n + with n ≦26, we identified another series of NO(N2O) m + with m =0–12 as well as O2 + and N3 + products characteristic of ion-molecule reactions within the clusters. Photoelectron–photoion–photoion-coincidence (PEPIPICO) technique was applied to study dissociation mechanisms and dynamics of core-excited (N2O) n clusters. Charge separation mechanisms of the doubly charged (N2O) n 2+ clusters by Nt(1s→π*) excitation were interpreted in terms of kinetic energy release (KER) and charge separation distance (CSD). [Copyright &y& Elsevier]

Abstract: Total photoabsorption spectra of CF3COCH3 were measured in the C, F and O K-shell regions and the peak assignments were tentatively given. The K-shell electrons of C, F and O atoms were selectively excited into the π* orbital. The kinetic energy (KE) distribution of CF3 + formed through the π* states gave the maxima at KE=0 and 0.43eV. The yield of CF3 + with KE=0eV increased from 10 to 50% by changing the excitation sites from F 1s to O 1s. This finding was reasonably understood by considering that intramolecular energy flows from the initially excited K-shell electron to vibrational modes of CF3 group. The KE distribution of CH3 + showed a mirror image of that for CF3 +. [Copyright &y& Elsevier]

Normal Auger electron spectra from Kr2p hole states, L[sub 23]M[sub 45]M[sub 45] and L[sub 23]M[sub 23]M[sub 45], have been measured using monochromatized synchrotron radiation and a high resolution electron spectrometer. Measured spectra were reproduced with a fitting calculation, where Voigt functions including an instrumental resolution and natural lifetime widths of related core hole states were used. At most final states estimated energies for spectral peaks agree with those by electron and ion beam techniques. Relative intensities for some peaks are appreciably different from the previous results. [ABSTRACT FROM AUTHOR]

A spectrometer for soft X-ray emission spectroscopy was designed and constructed. The aims of this spectrometer are high detection efficiency and realizing the energy resolution of 1000 (E/ΔE) in a compact size. To satisfy these requirements, a flat field spectrometer with a varied line spacing grating and a CCD detector was chosen. Furthermore, the configuration without the entrance slit was employed. For compact flat field spectrometers, the spectral dispersion on the detector is sometimes smaller than the spatial resolution of existing detectors restricting maximum energy resolution. The spectral dispersion on the detector was optimized to balance with the spatial resolution of CCD. Optical performance was tested with a ray-tracing program. The spectrometer covers 250-900 eV, with two gratings. Taking into account the spatial resolution of a CCD detector, the maximum energy resolution of the spectrometer is estimated to be about 1000 (E/ΔE) for the beam size of l0 µm. Using the constructed spectrometer, test experiments were performed at the beamline BL27SU in SPring-8. [ABSTRACT FROM AUTHOR]

Abstract: We have measured high-resolution total- and partial-ion yield spectra of NH3. The obtained total-ion yield spectrum exhibits more detailed structure than the absorption spectrum reported previously. The observed structure at the N 1s  3sa1 resonance is assigned as the vibrational progressions of symmetric stretching and bending mode. A dissociation channel mediated by the vibrational motion in the core-excited state of NH3 was observed. We focus on this vibrational structure and the formation process of , which remarkably depends on the vibrational state (and/or energy) in the core-excited state. [Copyright &y& Elsevier]

Describes the design concept of a spherical grating monochromator with translational and rotational assembly including a normal incidence mount (SGM-TRAIN) that is under construction at beamline 5A of the UltraViolet Synchrotron Orbital Radiation facility in Japan. Design requirements; Photon energy; Driving modes; Ways to suppress the higher-order light.

The valence electronic structures of the amino acid glycine in aqueous solution were investigated in detail through X-ray emission spectroscopy at O 1s excitation under selective excitation conditions of the C[double bond, length as m-dash]O site in the carboxyl group. The X-ray emission spectra of glycine were similar to that of acetic acid (CH3COOH), suggesting a resemblance between the molecular orbitals associated with the carboxyl groups in the two molecules. The changes of O 1s X-ray emission spectra as a function of pH were investigated in detail. In addition to spectral changes due to protonation/deprotonation of the carboxyl group for lower pH-values around the pKa value (∼2.3), the spectra of glycine exhibited further changes in the higher-pH region near the pKb value of glycine (dissociation constant of amino group ∼9.5). These results show the effects of amino group protonation on the electronic state around the carboxyl group. X-ray emission spectroscopy might be a tool to investigate intramolecular interactions between functional groups in a molecule.

Fragmentation of doubly charged ethanol clusters [(C(2)H(5)OH)(n)] following the O 1s ionization has been investigated by means of the photoelectron-photoion-photoion coincidence (PEPIPICO) method. The dominant fission channel of (C(2)H(5)OH)(n)(2+) was the formation of protonated cluster ion pairs [H(C(2)H(5)OH)(l)(+)/H(C(2)H(5)OH)(m)(+)]. The fragmentation mechanisms of these ion pairs were discussed based on the analysis of the PEPIPICO contour shape. It was clarified that the prominent fragmentation channel was a secondary decay mechanism, where neutral evaporation occurs after charge separation. On the other hand, the formation of small fragment ions was suppressed, excluding the formation of certain specific fragments (H(3)O(+), C(2)H(5)(+)/COH(+), and C(2)H(4)OH(+)). The formation of small fragment ions was suppressed due to the cooling effect caused by the neutral evaporation and the decrease in the electrostatic repulsive force caused by charge separation., (© 2011 American Institute of Physics)

Pronounced polarization dependence of the X-ray emission spectrum, which reflects the symmetry of the initial valence molecular orbital, was observed for acetic acid in acetonitrile solution under ambient conditions.

Occupied valence electronic structures in the neutral and the anionic forms of aqueous acetic acid and their pH dependence under ambient condition are identified for the first time exploiting the site-selectivity of resonant X-ray emission spectroscopy (XES) in combination with calculation based on density functional theory (DFT).

A study of the excitation energy dependence of resonant X-ray emission spectra across the O1s absorption edge in combination with X-ray absorption spectroscopy and density functional theory reveals the site-specific valence electronic structure of liquid acetic acid under ambient conditions.

Hydrogen bonding in methanol clusters has been investigated by using inner-shell photoabsorption spectroscopy and density functional theory (DFT) calculations in the carbon and oxygen K-edge regions. The partial-ion-yield (PIY) curves of H(CH(3)OH)(n)(+) were measured as the soft x-ray absorption spectra of methanol clusters. The first resonance peak in the PIY curves, which is assigned to the sigma*(O-H) resonance transition, exhibits a 1.20 eV blueshift relative to the total-ion-yield (TIY) curves of molecular methanol in the oxygen K-edge region, while it exhibits a shift of only 0.25 eV in the carbon K-edge region. Decreased intensities of the transitions to higher Rydberg orbitals were observed in the PIY curves of the clusters. The drastic change in the sigma*(O-H) resonance transition is interpreted by the change in the character of the sigma*(O-H) molecular orbital at the H-donating OH site due to the hydrogen-bonding interaction.

Dissociation of free methyl-formate (MF), HC(O)OCH3, and its clusters (MF)n, (HC(O)OCH3)n, induced by core-level excitation was studied near the oxygen K edge by time-of-flight fragment-mass spectroscopy. Besides the protonated clusters, (MF)nH+ with n < or = 15, we identified the production for another series of (MF)mCH3OH2+ with m < or = 14 as well as methyl-oxonium ion, CH3OH2+, characteristic of hydrogen transfer reactions in the cationic clusters. Here; specifically labeled methyl-formate-d (MFD), DC(O)OCH3 was also used to examine the core-excited dissociation mechanisms. Deuterium-labeled experiments indicated that MFD+ with low internal energies, partially generated after the core excitation, produces CH3OD+ via a site-specific deuterium transfer from the alpha carbonyl in the molecular cation and that CH3OD2+ can be formed via the successive transfer of another deuterium from the neighbor molecule in the clusters. The deuteron (proton) transfer was also found to take place preferentially from the alpha carbonyl of the neighbor molecule for the production of deuteronated (MFD)nD+, (protonated (MF)nH+), clusters. The minimal energy requirement paths were examined for dimer (MF)2+ cation to support the present dissociation mechanisms of core-excited (MF)n clusters using ab initio molecular-orbital calculations.

We have studied amino acid formation by UV (193 nm) irradiation to organic molecules (amines, alcohols and amides) in aqueous solution. Among several types of detected amino acids, small aliphatic amino acids (Gly and alpha-, beta-Ala and alpha-, beta-, gamma-ABA) were quantitatively identified. Among these small aliphatic amino acids, certain amino acids were formed in its free form, even before hydrolysis, contrary to the results of UV irradiation to a gas mixture of CO, NH3, and H2O, where amino acids were hardly detected before hydrolysis. The species distribution of identified amino acids showed a dependence on the starting organic molecules, and also on the presence of ammonia. The formation processes of the identified small aliphatic amino acids were investigated with the aid of electrospray ionization (ESI) MS and MS/MS measurements of photoproducts. Possible formation processes of these amino acid precursors from each starting molecules are proposed. By identifying the amino acid precursor, which has a chiral carbon atom, a new possibility is suggested for asymmetric photosynthesis of amino acid from achiral organic molecules.

Vibrationally resolved spectra have been obtained for the lowest-lying cationic states X (2)B(1), A (2)A(1), and B (2)B(2) of the water molecule reached after participator resonant Auger decay of core-excited states. The angular distribution has been measured of the first four vibrational components of the X state in the photon energy regions including the O 1s-->4a(1) and the O 1s-->2b(2) core excitations, and for different portions of the vibrational envelope of the B state in the photon energy region including the O 1s-->2b(2) core excitation. For the X state, a large relative spread in beta values of the different vibrational components is observed across both resonances. For the B state, a very different trend is observed for the high binding energy side and the low binding energy side of the related spectral feature as a function of photon energy. A theoretical method based on the scattering K matrix has been used to calculate both the photoabsorption spectrum and the beta values, by taking both interference between direct and resonant photoemission and vibrational/lifetime interference into account. The numerical results show qualitative agreement with the trends detected in the experimental values and explain the conspicuous variations of the beta values primarily in terms of coupling between direct and resonant photoemission by interaction terms of different sign for different final vibrational states.

Design and construction of a soft X-ray beamline at SPring-8 is reported. The beamline utilizes high-quality linearly polarized soft X-rays obtainable from a figure-8 undulator for the study of photophysical and photochemical processes of atoms, molecules and surfaces in the inner-shell excitation region. It consists of two experimental stations, a photochemistry station and a chemical vapour deposition (CVD) station. A high-resolution grating monochromator is installed at the photochemistry station, while the intense undispersed undulator radiation is used at the CVD station. Unique features of the experimental chambers and of the analysis and characterization systems are described along with those of the monochromator.

A compact racetrack-type 700 MeV storage ring (HiSOR) has been constructed at Hiroshima Synchrotron Radiation Center (HSRC). As the ring was planned for synchrotron radiation research on science and technology using VUV to X-rays up to 5 keV with limited size and cost, the ring was designed (i) to realize a high magnetic field (2.7 T) using conventional dipole magnets for higher critical energy, and (ii) to include two straight sections for insertion devices. A linear undulator (25-300 eV) and a new-type helical/linear undulator were installed at the two straight sections. The latter undulator consists of upper and lower jaws, as in a planar undulator; each jaw consists of one fixed magnet array at the centre and two magnet arrays on both sides. By longitudinal displacement of the side magnet arrays, the phase between the vertical and horizontal magnetic fields, and therefore the polarization (right- or left-circular, elliptical, linear) can be selected. The helical/linear undulator gives almost perfect circular polarization at 4-40 eV in the helical configuration without changing the phase of the magnet arrays, as well as linearly polarized light at 3-300 eV in the linear configuration.

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.

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 monochromated 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*(1s2p 1P), produced by primary synchrotron radiation excitation.