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David Lee Phillips - One of the best experts on this subject based on the ideXlab platform.
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Nanosecond Time-resolved resonance Raman investigation of the radical cation of 4,4′-dibromobiphenyl and the T1→Tn transition of 4,4′-dibromobiphenyl
Chemical Physics Letters, 1998Co-Authors: Duo-hai Pan, Lian C.t. Shoute, David Lee PhillipsAbstract:Abstract We have taken Nanosecond Time-resolved resonance Raman spectra of the T 1 →T n transition of 4,4′-dibromobiphenyl in cyclohexane solution and of the radical cation of 4,4′-dibromobiphenyl in acetonitrile solution. The resonance Raman spectrum of T 1 4,4′-dibromobiphenyl is consistent with a planar quinoidal structure. The C–Br bond appears stronger in the T 1 state than in the S 0 ground state and this is in agreement with photochemistry studies done for 4-bromobiphenyl that indicate that the T 1 state must be further excited by excimer formation and/or electron transfer with an appropriate donor prior to a debromination reaction.
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Nanosecond Time-resolved resonance Raman investigation of the T1→Tn transition of 2-bromonaphthalene
Chemical Physics Letters, 1998Co-Authors: Lian C.t. Shoute, Duo-hai Pan, David Lee PhillipsAbstract:Abstract We have obtained Nanosecond Time-resolved resonance Raman spectra of the T 1 →T n transition of 2-bromonaphthalene in methanol solvent. The transient resonance Raman spectra indicate that there are mostly structural changes in the C–C stretch ν 5a vibrational coordinate along with a smaller amount of change in the C–Br stretch and C–Br in plane deformation coordinates. This suggests that the T 1 →T n transition of 2-bromonaphthalene does not initially excite a directly dissociative triplet state and a predissociative mechanism is probably responsible for the efficient T n state C–Br bond cleavage found in previous photochemistry studies.
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Nanosecond Time-resolved resonance Raman investigation of the T1→Tn transition of 2-bromonaphthalene
Chemical Physics Letters, 1998Co-Authors: Lian C.t. Shoute, Duo-hai Pan, David Lee PhillipsAbstract:We have obtained Nanosecond Time-resolved resonance Raman spectra of the T1→Tn transition of 2-bromonaphthalene in methanol solvent. The transient resonance Raman spectra indicate that there are mostly structural changes in the C-C stretch ν5a vibrational coordinate along with a smaller amount of change in the C-Br stretch and C-Br in plane deformation coordinates. This suggests that the T1→Tn transition of 2-bromonaphthalene does not initially excite a directly dissociative triplet state and a predissociative mechanism is probably responsible for the efficient Tn state C-Br bond cleavage found in previous photochemistry studies.link_to_subscribed_fulltex
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Nanosecond Time-resolved resonance Raman investigation of the radical cation of 4,4′-dibromobiphenyl and the T1→T transition of 4,4′-dibromobiphenyl
Chemical Physics Letters, 1998Co-Authors: Duo-hai Pan, Lian C.t. Shoute, David Lee PhillipsAbstract:We have taken Nanosecond Time-resolved resonance Raman spectra of the T1 → Tn transition of 4,4′-dibromobiphenyl in cyclohexane solution and of the radical cation of 4,4′-dibromobiphenyl in acetonitrile solution. The resonance Raman spectrum of T1 4,4′-dibromobiphenyl is consistent with a planar quinoidal structure. The C-Br bond appears stronger in the T1 state than in the S0 ground state and this is in agreement with photochemistry studies done for 4-bromobiphenyl that indicate that the T1 state must be further excited by excimer formation and/or electron transfer with an appropriate donor prior to a debromination reaction.link_to_subscribed_fulltex
Hiro-o Hamaguchi - One of the best experts on this subject based on the ideXlab platform.
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Nanosecond Time-resolved Infrared Spectra and Structure of the Charge-transfer State of 9,9′-Bianthryl in Acetonitrile
Chemistry Letters, 2012Co-Authors: Nobuyuki Asami, Hiro-o Hamaguchi, Sohshi Yabumoto, Shinsuke Shigeto, Tomohisa Takaya, Koichi IwataAbstract:Nanosecond Time-resolved infrared spectra of photoexcited 9,9′-bianthryl (BA) and its deuterated derivative (BA-d18) were recorded in acetonitrile-d3 and cyclohexane-d12. The charge-transfer (CT) b...
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Triplet quantum chain process in the photoisomerization of 9-cis retinal as revealed by Nanosecond Time-resolved infrared spectroscopy
Journal of Molecular Structure, 2010Co-Authors: Tetsuro Yuzawa, Hiro-o HamaguchiAbstract:Abstract The mechanism of the photoisomerization of 9- cis retinal has been studied by Nanosecond Time-resolved infrared spectroscopy. A cyclohexane solution of 9- cis retinal was photoexcited at 349 nm and the subsequent photodynamics were traced. A singular value decomposition (SVD) analysis of the Time-resolved infrared data shows that there are two distinct isomerization pathways. One is the triplet pathway that takes place in the picosecond Time regime from 9- cis to all- trans . The other involves the energy transfer between the all- trans triplet state and the 9- cis ground state with the resultant 9- cis triplet state subsequently reproducing the all- trans by fast isomerization on the triplet potential surface . This quantum chain process occurs in the microsecond Time regime.
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Nanosecond Time-resolved infrared spectroscopy distinguishes two K species in the bacteriorhodopsin photocycle
Biophysical journal, 1995Co-Authors: Jun Sasaki, Tetsuro Yuzawa, Hideki Kandori, Akio Maeda, Hiro-o HamaguchiAbstract:The photochemical reaction process of bacteriorhodopsin in the Nanosecond Time range (-120–860 ns) was measured in the 1400–900 cm-1 region with an improved Time resolved dispersive-type infrared spectrometer. The system is equipped with a newly developed detection unit whose instrumental response to a 5-ns laser pulse has a full width of the half-maximum of 60 ns. It provides highly accurate data that enabled us to extract a kinetic process one order of magnitude faster than the instrumental response. The spectral changes in the 1400–900 cm-1 region were analyzed by singular value decomposition and resolved into three components. These components were separated by fitting with 10- and 1000-ns exponential functions and a step function, which were convoluted with the instrumental response function. The components with decay Time constants of 10 and 1000 ns are named K and KL, respectively, on the basis of previous visible spectroscopy. The spectral shapes of K and KL are distinguishable by their hydrogen-out-of-plane (HOOP) modes, at 958 and 984 cm-1, respectively. The former corresponds to the K intermediate recorded at 77 K and the latter to a K-like photoproduct at 135 K. On the basis of published data, these bands are assigned to the 15-HOOP mode, indicating that the K and KL differ in a twist around the C14-C15 bond.
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Investigation of the photoisomerization of all-trans-retinal by singular-value-decomposition analysis of Nanosecond Time-resolved infrared spectra
Journal of Molecular Structure, 1995Co-Authors: Tetsuro Yuzawa, Hiro-o HamaguchiAbstract:Abstract Nanosecond Time-resolved infrared spectroscopy has been used to study the photoisomerization of all- trans -retinal in cyclohexane. Singular-value-decomposition analysis of the observed Time-resolved infrared spectra shows that three species are generated after the photoexcitation of all- trans -retinal. One is the “all-trans” triplet species, which exclusively relaxes back to the all-trans form in the ground state with a Time constant of 5 μs. The other two are the 13-cis and 9-cis isomers in the ground state, which exhibit very rapid (
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Nanosecond Time-Resolved Infrared Spectroscopy with a Dispersive Scanning Spectrometer
Applied Spectroscopy, 1994Co-Authors: Tetsuro Yuzawa, Michael W. George, Chihiro Kato, Hiro-o HamaguchiAbstract:A Nanosecond Time-resolved infrared spectroscopic system based on a dispersive scanning spectrometer has been constructed. This is an advanced version of a similar system reported in a previous paper; the Time resolution has been improved from 1 μs to 50 ns and the sensitivity from 10-4 in intensity changes to 10-6. These have been achieved by the use of a high-temperature ceramic infrared light source, a photovoltaic MCT detector, and a low-noise, wide-band preamplifier developed specifically for the present purpose. Time-resolved infrared spectra of a few samples of photochemical and photobiological interests are presented to show the capability of the system. The origin of the thermal artifacts, which have been found to hamper the Time-resolved infrared measurements seriously, is shown to be due to the transient reflectance change induced by a small temperature jump. The future prospect of Time-resolved infrared spectroscopy is discussed with reference to other methods including infrared laser spectroscopy and Fourier transform infrared spectroscopy.
Lian C.t. Shoute - One of the best experts on this subject based on the ideXlab platform.
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Nanosecond Time-resolved resonance Raman investigation of the radical cation of 4,4′-dibromobiphenyl and the T1→Tn transition of 4,4′-dibromobiphenyl
Chemical Physics Letters, 1998Co-Authors: Duo-hai Pan, Lian C.t. Shoute, David Lee PhillipsAbstract:Abstract We have taken Nanosecond Time-resolved resonance Raman spectra of the T 1 →T n transition of 4,4′-dibromobiphenyl in cyclohexane solution and of the radical cation of 4,4′-dibromobiphenyl in acetonitrile solution. The resonance Raman spectrum of T 1 4,4′-dibromobiphenyl is consistent with a planar quinoidal structure. The C–Br bond appears stronger in the T 1 state than in the S 0 ground state and this is in agreement with photochemistry studies done for 4-bromobiphenyl that indicate that the T 1 state must be further excited by excimer formation and/or electron transfer with an appropriate donor prior to a debromination reaction.
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Nanosecond Time-resolved resonance Raman investigation of the T1→Tn transition of 2-bromonaphthalene
Chemical Physics Letters, 1998Co-Authors: Lian C.t. Shoute, Duo-hai Pan, David Lee PhillipsAbstract:Abstract We have obtained Nanosecond Time-resolved resonance Raman spectra of the T 1 →T n transition of 2-bromonaphthalene in methanol solvent. The transient resonance Raman spectra indicate that there are mostly structural changes in the C–C stretch ν 5a vibrational coordinate along with a smaller amount of change in the C–Br stretch and C–Br in plane deformation coordinates. This suggests that the T 1 →T n transition of 2-bromonaphthalene does not initially excite a directly dissociative triplet state and a predissociative mechanism is probably responsible for the efficient T n state C–Br bond cleavage found in previous photochemistry studies.
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Nanosecond Time-resolved resonance Raman investigation of the T1→Tn transition of 2-bromonaphthalene
Chemical Physics Letters, 1998Co-Authors: Lian C.t. Shoute, Duo-hai Pan, David Lee PhillipsAbstract:We have obtained Nanosecond Time-resolved resonance Raman spectra of the T1→Tn transition of 2-bromonaphthalene in methanol solvent. The transient resonance Raman spectra indicate that there are mostly structural changes in the C-C stretch ν5a vibrational coordinate along with a smaller amount of change in the C-Br stretch and C-Br in plane deformation coordinates. This suggests that the T1→Tn transition of 2-bromonaphthalene does not initially excite a directly dissociative triplet state and a predissociative mechanism is probably responsible for the efficient Tn state C-Br bond cleavage found in previous photochemistry studies.link_to_subscribed_fulltex
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Nanosecond Time-resolved resonance Raman investigation of the radical cation of 4,4′-dibromobiphenyl and the T1→T transition of 4,4′-dibromobiphenyl
Chemical Physics Letters, 1998Co-Authors: Duo-hai Pan, Lian C.t. Shoute, David Lee PhillipsAbstract:We have taken Nanosecond Time-resolved resonance Raman spectra of the T1 → Tn transition of 4,4′-dibromobiphenyl in cyclohexane solution and of the radical cation of 4,4′-dibromobiphenyl in acetonitrile solution. The resonance Raman spectrum of T1 4,4′-dibromobiphenyl is consistent with a planar quinoidal structure. The C-Br bond appears stronger in the T1 state than in the S0 ground state and this is in agreement with photochemistry studies done for 4-bromobiphenyl that indicate that the T1 state must be further excited by excimer formation and/or electron transfer with an appropriate donor prior to a debromination reaction.link_to_subscribed_fulltex
A. Materny - One of the best experts on this subject based on the ideXlab platform.
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Nanosecond Time‐Resolved Resonance CARS Spectroscopy of Triplet Excited Polycyclic Aromatic Compounds
Spectroscopy Letters, 2003Co-Authors: J.-m. Funk, C. Eichhorn, Wolfgang Kiefer, A. MaternyAbstract:We use Time‐resolved resonance CARS spectroscopy as a diagnostic approach to study the structure and the dynamics of photoinduced transient molecular species. Transient CARS spectra of several highly fluorescent organic molecules in the lowest excited triplet state are reported and discussed. Several fundamentals of anthracene and some monosubstituted derivatives are observed and assigned unambiguously by comparison of the S0 and T1 spectral features. Moreover, it is verified that the most intense CC stretching band of anthracene in the lowest excited triplet state exhibits an upward wavenumber shift upon deuteration. Nanosecond Time‐resolved transient CARS spectroscopy opens up the possibility to study the triplet relaxation process of the sample molecules. Furthermore, it is shown by means of transient CARS spectroscopy that the lowest excited triplet state of 9‐fluorenone exhibits ππ * character. The wavenumbers of the transient CO and CC stretching modes differ considerably from the appropriate Raman ...
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Nanosecond Time-RESOLVED RESONANCE CARS SPECTROSCOPY USING THE SCANNING MULTICHANNEL TECHNIQUE
Applied Spectroscopy, 1998Co-Authors: J.-m. Funk, T. Michelis, R. Eck, A. MaternyAbstract:We report on an experimental setup which has been developed to perform efficient Nanosecond Time-resolved coherent anti-Stokes Raman scattering (CARS) experiments using either the scanning CARS or the broadband CARS technique. A special electronic device has been constructed that allows the CARS probing laser system to be triggered with a variable delay after the excitation pulse of a nitrogen laser and furthermore prevents any temporal drifts of the nitrogen laser emission. The acquisition of the broadband CARS spectra is based on the recently developed scanning multi-channel technique, which is applied in the present paper to CARS spectroscopy. Several examples of ground- and excited-state CARS spectra are shown to demonstrate the performance of the setup and to point out the benefits and limitations of the various measurement techniques. Moreover, we present CARS spectroscopic investigations of triplet relaxation processes in order to illustrate the feasibility of the designed spectrometer for Nanosecond Time-resolved CARS experiments.
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ANALYSIS OF THE THIRD-ORDER SUSCEPTIBILITIES OF TRIPLET EXCITED MOLECULES USING Nanosecond Time-RESOLVED RESONANCE CARS
Journal of Raman Spectroscopy, 1998Co-Authors: J.-m. Funk, A. MaternyAbstract:Nanosecond Time-resolved resonance CARS spectra of anthracene and 9,10-dichloroanthracene in the lowest excited triplet state are reported. Simultaneous fitting of a series of Time-resolved CARS spectra to appropriate lineshape equations was used to determine the molecular third-order susceptibility parameters of these electronic excited state molecules unambiguously. The capability of this method to study the resonance behaviour of these parameters is demonstrated by the determination of the sign of the imaginary part I of the Raman resonant CARS susceptibility of T1 triplet anthracene at two different pump laser wavelengths. © 1998 John Wiley & Sons.
Duo-hai Pan - One of the best experts on this subject based on the ideXlab platform.
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Nanosecond Time-resolved resonance Raman investigation of the radical cation of 4,4′-dibromobiphenyl and the T1→Tn transition of 4,4′-dibromobiphenyl
Chemical Physics Letters, 1998Co-Authors: Duo-hai Pan, Lian C.t. Shoute, David Lee PhillipsAbstract:Abstract We have taken Nanosecond Time-resolved resonance Raman spectra of the T 1 →T n transition of 4,4′-dibromobiphenyl in cyclohexane solution and of the radical cation of 4,4′-dibromobiphenyl in acetonitrile solution. The resonance Raman spectrum of T 1 4,4′-dibromobiphenyl is consistent with a planar quinoidal structure. The C–Br bond appears stronger in the T 1 state than in the S 0 ground state and this is in agreement with photochemistry studies done for 4-bromobiphenyl that indicate that the T 1 state must be further excited by excimer formation and/or electron transfer with an appropriate donor prior to a debromination reaction.
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Nanosecond Time-resolved resonance Raman investigation of the T1→Tn transition of 2-bromonaphthalene
Chemical Physics Letters, 1998Co-Authors: Lian C.t. Shoute, Duo-hai Pan, David Lee PhillipsAbstract:Abstract We have obtained Nanosecond Time-resolved resonance Raman spectra of the T 1 →T n transition of 2-bromonaphthalene in methanol solvent. The transient resonance Raman spectra indicate that there are mostly structural changes in the C–C stretch ν 5a vibrational coordinate along with a smaller amount of change in the C–Br stretch and C–Br in plane deformation coordinates. This suggests that the T 1 →T n transition of 2-bromonaphthalene does not initially excite a directly dissociative triplet state and a predissociative mechanism is probably responsible for the efficient T n state C–Br bond cleavage found in previous photochemistry studies.
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Nanosecond Time-resolved resonance Raman investigation of the T1→Tn transition of 2-bromonaphthalene
Chemical Physics Letters, 1998Co-Authors: Lian C.t. Shoute, Duo-hai Pan, David Lee PhillipsAbstract:We have obtained Nanosecond Time-resolved resonance Raman spectra of the T1→Tn transition of 2-bromonaphthalene in methanol solvent. The transient resonance Raman spectra indicate that there are mostly structural changes in the C-C stretch ν5a vibrational coordinate along with a smaller amount of change in the C-Br stretch and C-Br in plane deformation coordinates. This suggests that the T1→Tn transition of 2-bromonaphthalene does not initially excite a directly dissociative triplet state and a predissociative mechanism is probably responsible for the efficient Tn state C-Br bond cleavage found in previous photochemistry studies.link_to_subscribed_fulltex
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Nanosecond Time-resolved resonance Raman investigation of the radical cation of 4,4′-dibromobiphenyl and the T1→T transition of 4,4′-dibromobiphenyl
Chemical Physics Letters, 1998Co-Authors: Duo-hai Pan, Lian C.t. Shoute, David Lee PhillipsAbstract:We have taken Nanosecond Time-resolved resonance Raman spectra of the T1 → Tn transition of 4,4′-dibromobiphenyl in cyclohexane solution and of the radical cation of 4,4′-dibromobiphenyl in acetonitrile solution. The resonance Raman spectrum of T1 4,4′-dibromobiphenyl is consistent with a planar quinoidal structure. The C-Br bond appears stronger in the T1 state than in the S0 ground state and this is in agreement with photochemistry studies done for 4-bromobiphenyl that indicate that the T1 state must be further excited by excimer formation and/or electron transfer with an appropriate donor prior to a debromination reaction.link_to_subscribed_fulltex
