The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
Teiichiro Ogawa - One of the best experts on this subject based on the ideXlab platform.
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Dependence of the laser Two-Photon Ionization process in solution on the laser pulse width.
Analytical chemistry, 2001Co-Authors: Teiichiro Ogawa, Masahiro Mizutani, Takanori InoueAbstract:The laser Two-Photon Ionization process has been investigated using simultaneous irradiation of an UV beam and an IR beam. When the laser pulse width was 300 ps, it proceeded through a geminate pair state (a stepwise process), as indicated by the signal enhancement with simultaneous irradiation of the two laser beams. Although no signal enhancement was observed when the laser pulse width was 100 fs, and because molecules with no absorption at the laser wavelength showed an intense signal, the Two-Photon Ionization excited by a femtosecond laser should proceed through a simultaneous Two-Photon process. The detection limit was quite susceptible to the laser fluctuations.
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Two-Color Two-Photon Ionization Spectrum of Pyrene in N-Hexane
Laser Chemistry, 1997Co-Authors: Keiji Nakashima, Hirofumi Soga, Teiichiro OgawaAbstract:The photoIonization process of pyrene in non-polar solvent has been investigated using a two-color Two-Photon Ionization technique. The Ionization spectrum near threshold of pyrene in n-hexane was measured by a delayed irradiation of a dye laser 20 ns after an N2 laser at total excitation energies of 5.9–6.22 eV. The Two-Photon Ionization threshold of pyrene was in the vicinity of 5.9 eV which is larger by 0.7 eV than that expected from the onset of one-photon Ionization. The Ionization spectrum shows maxima at 5.92 and 5.99 eV which may be assigned to an autoIonization process.
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Highly Sensitive Detection of Pyrene in A Flow Jet by Surface Laser Two-Photon Ionization
Instrumentation Science & Technology, 1995Co-Authors: Teiichiro Ogawa, Shinichiro Sumi, Takanori InoueAbstract:Abstract The laser Two-Photon Ionization technique has been applied to an aqueous flow in order to indicate an analytical potential of this technique to an HPLC detector. Irradiation at the surface of the flow showed a wider linear dynamic range of the analytical curve. The detection limit of pyrene was 0.08 μg/dm3.
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Time-delayed two-color Two-Photon Ionization of anthracene, benzo [a] pyrene and pyrene in cyclohexane
Chemical Physics Letters, 1994Co-Authors: Keiji Nakashima, Teiichiro Ogawa, Hirofumi Kawazumi, Manabu Kise, Sunao YamadaAbstract:Abstract Intermediate states of the Two-Photon Ionization of the three aromatic molecules in cyclohexane were investigated using a time-delayed two-color technique. The S 1 state is a major intermediate for the Two-Photon Ionization of anthracene and benzo [a] pyrene, while both the S 1 and S 2 states are intermediates for pyrene. Ionization through the short-lived S 2 state was enhanced through autoIonization resonance.
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Two-Photon Ionization of Naphthacene in Hexane Excited by an Argon Ion Laser
Chemistry Letters, 1992Co-Authors: Hirofumi Kawazumi, Yuji Isoda, Teiichiro OgawaAbstract:A continuous wave laser can induce Two-Photon Ionization in solution. The conductivity signals of naphthacene in hexane excited by the 458-nm line of an argon ion laser were quadratically proportional to the laser power and linearly proportional to the solute concentration, indicating a Two-Photon process.
Hugo W Van Der Hart - One of the best experts on this subject based on the ideXlab platform.
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On the importance of inner-shell processes in Two-Photon Ionization of Ne+
Journal of Physics: Conference Series, 2009Co-Authors: Linda Hamonou, Michael Lysaght, Hugo W Van Der HartAbstract:We have investigated Two-Photon Ionization of ground-state Ne+ using the time-independent R-matrix Floquet approach and the time-dependent R-matrix approach. The R-matrix Floquet approach enables the detailed study of the influence of atomic structure on the magnitude of the Ionization rates. It is found that excitation processes involving the inner 2s electron substantially enhance the Two-Photon Ionization rates of Ne+. For photon energies above 37.5 eV, emission of the 2s electron becomes significant as demonstrated by the large probability that the residual Ne2+ ion is left in the 2s2p5 configuration. Time-dependent calculations of the Ionization probability as a function of pulse length correspond well with the R-matrix Floquet Ionization rates. However, the Ionization probability is enhanced by single-photon Ionization during the turn-on and turn-off of the laser pulse. In addition, the laser pulse leads to the population and depopulation of autoionizing states above the Ne2+ ground state during the pulse, and the final population left in these states strongly depends on pulse length.
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Single- and Two-Photon Ionization of Sr
Journal of Physics B: Atomic Molecular and Optical Physics, 2005Co-Authors: Martin Madine, Hugo W Van Der HartAbstract:Using the R-matrix Floquet approach we have calculated single- and Two-Photon Ionization cross sections for Sr within a model potential approach. The frequency ranges investigated range from 0.21 to 0.27 au and from 0.105 to 0.158 au. The results are in reasonable agreement with previous experimental and theoretical work. The Two-Photon cross sections are dominated by the 5s6p 1Po resonance. For the m = 0 level of this resonance, we obtain photoIonization cross sections ranging typically between 5 and 20 Mb. A comparison with results for Ca shows good similarity for single-photon Ionization, but significantly less agreement for Two-Photon Ionization.
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Single- and Two-Photon Ionization of neutral Ca
Journal of Physics B: Atomic Molecular and Optical Physics, 2003Co-Authors: Claire Mckenna, Hugo W Van Der HartAbstract:Using a combination of B-spline-based model potential techniques with R-matrix Floquet theory, we have carried out single-photon and Two-Photon Ionization calculations of Ca. Good quantitative agreement is obtained with experiment for the single-photon Ionization cross-section above the first threshold. We investigate the intensity dependence of the photoIonization spectra, and also illustrate how laser-induced degenerate states affect it. Inclusion of the spatial and temporal profile of the laser pulse is examined. The Two-Photon Ionization spectra, below the 3d2 De threshold, show a clear perturbation due to the interloping 4p21 Se state.
Sunao Yamada - One of the best experts on this subject based on the ideXlab platform.
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Time-delayed two-color Two-Photon Ionization of anthracene, benzo [a] pyrene and pyrene in cyclohexane
Chemical Physics Letters, 1994Co-Authors: Keiji Nakashima, Teiichiro Ogawa, Hirofumi Kawazumi, Manabu Kise, Sunao YamadaAbstract:Abstract Intermediate states of the Two-Photon Ionization of the three aromatic molecules in cyclohexane were investigated using a time-delayed two-color technique. The S 1 state is a major intermediate for the Two-Photon Ionization of anthracene and benzo [a] pyrene, while both the S 1 and S 2 states are intermediates for pyrene. Ionization through the short-lived S 2 state was enhanced through autoIonization resonance.
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Trace determination of benzene and aromatic molecules in hexane by laser Two-Photon Ionization
Analytical Chemistry, 1992Co-Authors: Teiichiro Ogawa, Hirofumi Kawazumi, Manabu Kise, To Oru Yasuda, Sunao YamadaAbstract:Laser Two-Photon Ionization of several aromatic molecules in hexane has been carried out with the fourth harmonics (266 nm) of a Nd-YAG laser as an excitation source. The photoIonization current is quadratically proportional to the laser pulse energy, indicating Two-Photon Ionization. There is a large blank signal due to the solvent (hexane) Ionization, and it has been canceled with a differential technique. The effect of laser pulse energy fluctuation has been corrected by an on-line normalization procedure
Michael D. Morse - One of the best experts on this subject based on the ideXlab platform.
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RESONANT Two-Photon Ionization SPECTROSCOPY OF LICU
The Journal of Chemical Physics, 1997Co-Authors: Larry M. Russon, Gretchen K. Rothschopf, Michael D. MorseAbstract:Jet-cooled LiCu has been investigated using resonant Two-Photon Ionization spectroscopy. A long vibrational progression was observed and identified as the [20.5] 1Σ+←X 1Σ+ band system. Ten bands of the system were rotationally resolved for 7Li63Cu, giving bond lengths of r0=2.2618(3) A for the X 1Σ+ state and re′=2.74(4) A for the [20.5] 1Σ+ state. The fitted spectroscopic parameters of the [20.5] 1Σ+ state were used to obtain a RKR estimate of the [20.5] 1Σ+ potential energy curve. The unusual shape of this curve is thought to derive from avoided crossings between the Li+Cu− ion pair state and covalent states, with the Li+Cu− ion pair state ultimately correlating to the ground electronic state of the molecule.
U. Sassenberg - One of the best experts on this subject based on the ideXlab platform.
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Resonant Two-Photon Ionization spectroscopy studies of jet-cooled
Journal of Physics B: Atomic Molecular and Optical Physics, 1998Co-Authors: Mats Doverstål, Lars Karlsson, B. Lindgren, U. SassenbergAbstract:Resonant Two-Photon Ionization spectroscopy in a jet-cooled molecular beam has been employed for the study of the zirconium dimer produced by laser ablation. More than 110 resonances have been observed in the wavelength region 610-1070 nm. Most of these resonances are transitions from of the ground state, which is shown to be a state, to different vibrational levels of the excited states. Three bands have been rotationally analysed. The ground state B-value is found to be . Radiative lifetimes have been measured for two excited states, both of them between 1 and .
