Sheng Hsien Lin

National Chiao Tung University, Hsin-chu-hsien, Taiwan, Taiwan

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Publications (134)396.63 Total impact

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    ABSTRACT: We generalize a theory of diffusion of a massive particle by the way in which transport characteristics are described by analytical expressions that formally coincide with those for the overdamped massless case but contain a factor comprising the particle mass which can be calculated in terms of Risken's matrix continued fraction method (MCFM). Using this generalization, we aim to elucidate how large gradients of a periodic potential affect the current in a tilted periodic potential and the average current of adiabatically driven on-off flashing ratchets. For this reason, we perform calculations for a sawtooth potential of the period L with an arbitrary sawtooth length (l<L) instead of the smooth potentials typically considered in MCFM-solvable problems. We find nonanalytic behavior of the transport characteristics calculated for the sharp extremely asymmetric sawtooth potential at l→0 which appears due to the inertial effect. Analysis of the temperature dependences of the quantities under study reveals the dominant role of inertia in the high-temperature region. In particular, we show, by the analytical strong-inertia approach developed for this region, that the temperature-dependent contribution to the mobility at zero force and to the related effective diffusion coefficient are proportional to T^{-3/2} and T^{-1/2}, respectively, and have a logarithmic singularity at l→0.
    No preview · Article · Jan 2016 · Physical Review E
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    Linyin Yan · Yan Wan · Andong Xia · Sheng Hsien Lin · Ran Huang
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    ABSTRACT: A multi-leveled theoretical investigation combining TD-DFT(B3LYP and CAM-B3LYP) methods and semi-empirical method has been conducted to determine the structure-related spectral properties for T-series dendrimers composed of nearly hundreds of atoms, which has been carried outbased on the proposed molecular model. Both one- and two-photon absorption spectra of these dendrimer molecules have been well reproduced. The “antenna effect” in the dendrimers molecule has been theoretically studied. The process of excitation energy localization from chromophores in branches to the pyrene core before the fluorescence emission is visualized by using the contour of charge different density (CDD) between electronic states. The conclusions based on the theoretical model have been drawn to the observed photophysical properties of T-series dendrimers: a). increasing a generation of branch would enhance the absorption of photons with wavelength below 430 nm; b). enlarging the conjugation of branches would enhance the coupling among the chromophores and lower the excitation energy; c). the existence of inter-molecular coupling among the “antenna” chromophores in conjugated branches and the pyrene core would significantly promote two photons absorption.
    Full-text · Article · Jan 2016 · Physical Chemistry Chemical Physics
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    ABSTRACT: The electron angular momentum is a fundamental quantity of high-symmetry aromatic ring molecules and finds many applications in chemistry such as molecular spectroscopy. The stationary angular momentum or unidirectional rotation of π electrons is generated by the excitation of a degenerated electronic excited state by a circularly-polarized photon. For low-symmetry aromatic ring molecules having non-degenerate states, such as chiral aromatic ring molecules, on the other hand, whether stationary angular momentum can be generated or not is uncertain and has not been clarified so far. We have found by both theoretical treatments and quantum optimal control (QOC) simulations that a stationary angular momentum can be generated even from a low-symmetry aromatic ring molecule. The generation mechanism can be explained in terms of the creation of a dressed-state, and the maximum angular momentum is generated by the dressed state with an equal contribution from the relevant two excited states in a simple three-electronic state model. The dressed state is formed by inducing selective nonresonant transitions between the ground and each excited state by two lasers with the same frequency but having different polarization directions. The selective excitation can be carried out by arranging each photon-polarization vector orthogonal to the electronic transition moment of the other transition. We have successfully analyzed the results of the QOC simulations of (P)-2,2'-biphenol of axial chirality in terms of the analytically determined optimal laser fields. The present findings may open up new types of chemical dynamics and spectroscopy by utilizing strong stationary ring currents and current-induced magnetic fields, which are created at a local site of large compounds such as biomolecules.
    No preview · Article · Dec 2015 · Physical Chemistry Chemical Physics
  • Elmar G Petrov · Bruno Robert · Sheng Hsien Lin · Leonas Valkunas
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    ABSTRACT: Theoretical consideration is presented of the triplet excitation dynamics in donor-acceptor systems in conditions where the transfer is mediated by an oxygen molecule. It is demonstrated that oxygen may be involved in both real and virtual intramolecular triplet-singlet conversions in the course of the process under consideration. Expressions describing a superexchange donor-acceptor coupling owing to a participation of the bridging twofold degenerate oxygen's virtual singlet state are derived and the transfer kinetics including the sequential (hopping) and coherent (distant) routes are analyzed. Applicability of this theoretical description to the pigment-protein complex cytochrome b6f, by considering the triplet excitation transfer from the chlorophyll a molecule to distant β-carotene, is discussed.
    No preview · Article · Oct 2015 · Biophysical Journal
  • Yu-Hui Liu · Sheng-Cheng Lan · Chaoyuan Zhu · Sheng Hsien Lin
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    ABSTRACT: The dynamics of the excited-state intramolecular proton-transfer (ESIPT) reaction of quinoline-pyrazole (QP) isomers, designated as QP-I and QP-II, has been investigated by means of time-dependent density functional theory (TDDFT). A lower barrier has been found in the potential energy curve for the lowest singlet excited state (S1) along the proton-transfer coordinate of QP-II compared to that of QP-I. However, this is at variance with a recent experimental report [J. Phys. Chem. A 2010, 114, 7886-7891], in which the authors proposed that the ESIPT reaction would only proceed in QP-I due to the absence of a PT emission for QP-II. Therefore, several deactivating pathways have been investigated to determine whether fluorescence quenching occurs in the PT form of QP-II (PT-II). The S1 state of PT-II has nπ* character, which is a well-known dark state. Moreover, the energy gap between the S1 and T2 states is only 0.29 eV, implying that an intersystem crossing (ISC) process would occur rapidly following the ESIPT reaction. Therefore, it is demonstrated that the ESIPT could successfully proceed in QP-II, and that the PT emission would be quenched by the ISC process.
    No preview · Article · Jun 2015 · The Journal of Physical Chemistry A
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    ABSTRACT: Control of mobile π-electrons is one of the fundamental issues in the organic optoelectronics for designing the next generation ultrafast switching devices. The optimal control simulations of coherent π-electron rotations in (P)-2,2’-biphenol, which is the typical nonplanar aromatic molecule with axial chirality, were performed by taking into account two types of the control targets: one is generation of the maximum π-angular momentum, and the other is the maintaining of the generated unidirectional angular momentum during a setting time duration. The optimal control pulse for each target is designed. The analysis of the simulation results shows that the effective maintaining of the unidirectional angular momentum can be realized by applying 2π pulse to one of the electronic excited states forming the coherent electronic state. The 2π pulse prevents the reverse rotation of the π-electrons by dumping the excited state population to the ground state and subsequently by pumping the population back to the excited state. The present results provide a theoretical basis for the designing next generation ultrafast switching devices made by organic aromatic molecules.
    No preview · Article · May 2015
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    ABSTRACT: In this paper, we theoretically and experimentally investigate the photophysical and chemical characteristics and absorption spectra of various ruthenium complexes in solution used as efficient dye-sensitized solar cells. The target molecules are two popular complexes, cis-[Ru(4,4’-COO-2,2’-bpy)2(X)2]4-, (X = NCS, Cl) and trans-terpyridyl Ru. The experimental absorption spectra of these molecules, which show strong spin-orbit (SO) coupling are simulated using first-order perturbation theory based on time-dependent density functional theory and quantum chemistry calculations. It turns out that the theory can simulate the experimental data very well, which indicates that SO coupling is very important and the mixing between singlet and triplet states is strong in these molecules because of the large SO coupling constant of the Ru atom. The exact absorption spectra can only be reproduced by including the perturbation by SO couplings. The physical and chemical differences between cis-[Ru(4,4’-COO-2,2’-bpy)2(X)2]4-, (X = NCS, Cl) and trans-terpyridyl Ru complexes are elucidated using natural bond orbital and natural transition orbital analyses. From these analyses, we have found that the two kinds of Ru complexes are quite different in terms of photoexitation response and chemical bonding between the central Ru atom and the surrounding ligands.
    Full-text · Article · Apr 2015 · Physical Chemistry Chemical Physics
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    ABSTRACT: With a deformed object of a rigid rod inside, the local dislocations may be tracked relatively easily with respect to the internal rigid rod. We apply this concept on protein folding-unfolding to track the internal structural changes of an unfolded protein in solution. Proposed here is a protein internal coordination based on the major axis X of an ellipsoidal protein and the stable intrinsic transition dipole moment μ of the protein during unfolding. In this methodology, small-angle X-ray scattering (SAXS) is used to provide the protein global morphologies in the native and unfolded states. Furthermore, time-resolved fluorescence anisotropy (TRFA) provides the relative orientation between X and μ of Trp59 of the model protein cytochrome c. Hence observed in the protein unfolding with denaturants, acid, urea, or GuHCl, is the elongation of the native protein conformation along a reoriented protein major axis; accompanied are the different extents of relocations of the terminal α helices and loop structures of the protein in the corresponding unfolding.
    No preview · Article · Jan 2015 · Physical Chemistry Chemical Physics
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    ABSTRACT: The pressure-dependent interactions between the ionic liquid mixture ([MPI][I1.5]) and nano-TiO2 surfaces have been studied up to 2.5 GPa. The results of infrared spectroscopic profiles of [MPI][I1.5] and [MPI][I1.5]/ nano-TiO2 indicated that no appreciable changes of the C-H stretching bands with the addition of nano-TiO2 were observed under ambient pressure. As the pressure was elevated to 0.7 GPa, the C-H stretching absorption of [MPI][I1.5] underwent band-narrowing and red-shifts in frequency. In contrast to the results of [MPI][I1.5], the spectra of [MPI][I1.5]/ nano-TiO2 do not show dramatic changes under high pressures. A possible explanation for this observation is the formation of certain pressure-enhanced C-H---nano-TiO2 interactions around the imidazolium C-H and alkyl C-H groups. As imidazolium C-H---I- is replaced by the weaker imidazolium C-H---polyiodide, the splitting of the imidazolium C-H stretching bands was observed. The experimental results indicate that both nano-TiO2 and polyiodides are capable of disturbing the self-assembly of ionic liquids. This study suggests the possibility to tune the efficiency of dye-sensitized solar cells via high pressure method.
    No preview · Article · Nov 2014 · Physical Chemistry Chemical Physics
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    Min‐Yeh Tsai · Jian‐Min Yuan · Sheng‐Hsien Lin
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    ABSTRACT: In this work, we present a kinetic analysis for protein aggregation using the kinetic Ising model, which serves as a new application of a previously proposed model [Liang et al., J. Chin. Chem. Soc.­ 2003, 50, 335]. Considering protein as a single spin unit, we map two states of a unit to the aggregation-prone (AP) and the fibril (F) states. This work shows that the model can successfully capture the nucleation-growth features of protein aggregation from experiments, which offers thermodynamic interpretations of aggregation properties, such as lag-time and fibril stability.
    Full-text · Article · Oct 2014
  • Jinghui Wang · Ming Li · Dan Qi · Wei Shen · Rongxing He · Sheng Hsien Lin
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    ABSTRACT: An efficient strategy was provided by adopting different number of electron-deficient units (pyrimidyl and quinolyl) into parent coumarin sensitizers to obtain excellent absorption in short-wavelength region (B2 band), which eventually improves the performance of DSSCs. Density functional theory calculations were performed on both free dyes and dye/TiO2 complexes. As expected, introducing single electron-deficient unit results in a positive influence on power conversion efficiency (η) of DSSCs because of the larger short-circuit current density (Jsc is proportional to optical absorption (φLHE), charge separation, dye regeneration (φreg) and electron injection (φinject)) and the higher open circuit voltage (Voc). The introduction of more pyrimidine facilitates charge separation and favors effective electron injection, whereas the second quinoline displays opposite effect. The results give a guidance to design promising candidates for the future DSSCs applications.
    No preview · Article · Oct 2014 · RSC Advances
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    ABSTRACT: Rationale: Although several reaction models have been proposed in the literature to explain matrix-assisted laser desorption/ionization (MALDI), further study is still necessary to explore the important ionization pathways that occur under the high-temperature environment of MALDI. 2,4,6-Trihydroxyacetophenone (THAP) is an ideal compound for evaluating the contribution of thermal energy to an initial reaction with minimum side reactions. Methods: Desorbed neutral THAP and ions were measured using a crossed-molecular beam machine and commercial MALDI-TOF instrument, respectively. A quantitative model incorporating an Arrhenius-type desorption rate derived from transition state theory was proposed. Reaction enthalpy was calculated using GAUSSIAN 03 software with dielectric effect. Additional evidence of thermal-induced proton disproportionation was given by the indirect ionization of THAP embedded in excess fullerene molecules excited by a 450 nm laser. Results: The quantitative model predicted that proton disproportionation of THAP would be achieved by thermal energy converted from a commonly used single UV laser photon. The dielectric effect reduced the reaction Gibbs free energy considerably even when the dielectric constant was reduced under high-temperature MALDI conditions. With minimum fitting parameters, observations of pure THAP and THAP mixed with fullerene both agreed with predictions. Conclusions: Proton disproportionation of solid THAP was energetically favorable with a single UV laser photon. The quantitative model revealed an important initial ionization pathway induced by the abrupt heating of matrix crystals. In the matrix crystals, the dielectric effect reduced reaction Gibbs free energy under typical MALDI conditions. The result suggested that thermal energy plays an important role in the initial ionization reaction of THAP.
    No preview · Article · Aug 2014 · Rapid Communications in Mass Spectrometry
  • Yibo Lei · Le Yu · Bo Zhou · Chaoyuan Zhu · Zhenyi Wen · Sheng Hsien Lin
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    ABSTRACT: The photoisomerization of cis- and trans-stilbene through conical intersections (CI) is mainly governed by four dihedral angles around central C = C double bonds. The two of them are C-C= C-C and H-C=C-H dihedral angles that are found to form mirror rotation coordinate, and the mirror plane appears at the two dihedral angles equal to zeros with which middle state is defined through partial optimization. There exist the first-type of Hula-Twist-CI enantiomers, the second-type of Hula-Twist-CI enantiomers, the first-type of one-bond-flip-CI enantiomers, and the second type of one-bond-flip-CI enantiomers as well as cis-enantiomers and trans-enantiomers with respect to this mirror plane. The complete active space self-consistent field method is employed to calculate minimum potential energy profile along the mirror rotation coordinate for each enantiomers, and it is found that the left-hand manifold and the right-hand manifold of potential energy surfaces can be energetically transferred via photoisomerization. Furthermore, two dimensional potential energy surfaces in terms of the branching plane g-h coordinates are constructed at vicinity of each conical intersection, and the landscapes of conical intersections show distinct feature, and in excited state four potential wells separated in different section of g-h plane related to different conical intersections which indicate different photoisomerization pathways.
    No preview · Article · Jun 2014 · The Journal of Physical Chemistry A
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    ABSTRACT: We consider a system of two coupled particles fluctuating between two states, with different interparticle interaction potentials and particle friction coefficients. An external action drives the interstate transitions that induces reciprocating motion along the internal coordinate x (the interparticle distance). The system moves unidirectionally due to rectification of the internal motion by asymmetric friction fluctuations and thus operates as a dimeric motor that converts input energy into net movement. We focus on how the law of interaction between the particles affects the dimer transport and, in particular, the role of thermal noise in the motion inducing mechanism. It is argued that if the interaction potential behaves at large distances as x(α), depending on the value of the exponent α, the thermal noise plays a constructive (α > 2), neutral (α = 2), or destructive (α < 2) role. In the case of α = 1, corresponding piecewise linear potential profiles, an exact solution is obtained and discussed in detail.
    No preview · Article · Jun 2014 · The Journal of Chemical Physics
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    ABSTRACT: Controlling π-electrons with delocalized character is one of the fundamental issues in femtosecond and attosecond chemistry. Localization of π-electron rotation by using laser pulses is expected to play an essential role in nanoscience. The π-electron rotation created at a selected aromatic ring of a single molecule induces a local intense electromagnetic field, which is a new type of ultrafast optical control functioning. We propose a quantum localization of coherent π-electron angular momentum in (P)-2,2′-biphenol, which is a simple, covalently linked chiral aromatic ring chain molecule. The localization considered here consists of sequential two steps: the first step is to localize the π-electron angular momentum at a selected ring of the two benzene rings, and the other is to maintain the localization. Optimal control theory was used for obtaining the optimized electric fields of linearly polarized laser pulses to realize the localization. The optimal electric fields and the resultant coherent electronic dynamics are analyzed.
    Full-text · Article · May 2014 · Journal of Physical Chemistry Letters
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    ABSTRACT: We study analytically the effect of a small inertial correction on the properties of adiabatically driven flashing ratchets. Parrondo's lemma [J. M. R. Parrondo, Phys. Rev. E 57, 7297 (1998)] is generalized to include the inertial term so as to establish the symmetry conditions allowing directed motion (other than in the overdamped massless case) and to obtain a high-temperature expansion of the motion velocity for arbitrary potential profiles. The inertial correction is thus shown to enhance the ratchet effect at all temperatures for sawtooth potentials and at high temperatures for simple potentials described by the first two harmonics. With the special choice of potentials represented by at least the first three harmonics, the correction gives rise to the motion reversal in the high-temperature region. In the low-temperature region, inertia weakens the ratchet effect, with the exception of the on-off model, where diffusion is important. The directed motion adiabatically driven by potential sign fluctuations, though forbidden in the overdamped limit, becomes possible due to purely inertial effects in neither symmetric nor antisymmetric potentials, i.e., not for commonly used sawtooth and two-sinusoid profiles.
    No preview · Article · May 2014 · Physical Review E
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    Chih-Kai Lin · Michitoshi Hayashi · Sheng Hsien Lin
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    ABSTRACT: Sum-frequency generation (SFG) spectroscopy is a powerful tool for not only identifying molecular species but also analyzing orientation configurations on a surface/interface. In this Article, we presented reformulation of the theoretical framework of electronic SFG spectroscopy, the signal of which could be greatly enhanced by tuning one or two incident beam frequencies resonant with electronic excited states. Simulated electronic SFG spectra resonant at the sum frequency of a pair of coumarin-derivative pH-indicator surfactant molecules, 4-methyl-7-hydroxycoumarin and its anionic counterpart (MHC/MHC–), floating on the water surface were carried out as a demonstration.
    Full-text · Article · Nov 2013 · The Journal of Physical Chemistry C
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    ABSTRACT: Multi-reference configuration interaction with single and double excitation method has been utilized to calculate the potential energy surfaces of the five low-lying electronic states (1)A1, (1)A2, (3)A2, (1)B2, and (3)B2 of carbon dioxide molecule. Topology of intersections among these five states has been fully analyzed and is associated with double-well potential energy structure for every electronic state. The analytical potential energy surfaces based on the reproducing kernel Hilbert space method have been utilized for illustrating topology of surface crossings. Double surface seam lines between (1)A1 and (3)B2 states have been found inside which the (3)B2 state is always lower in potential energy than the (1)A1 state, and thus it leads to an angle bias collision dynamics. Several conical∕surface intersections among these five low-lying states have been found to enrich dissociation pathways, and predissociation can even prefer bent-geometry channels. Especially, the dissociation of O((3)P) + CO can take place through the intersection between (3)B2 and (1)B2 states, and the intersection between (3)A2 and (1)B2 states.
    No preview · Article · Oct 2013 · The Journal of Chemical Physics
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    ABSTRACT: A series of dyes based on a porphyrin donor and a cyanoacrylic acid anchor/acceptor group for solar cell application are investigated with regards to varied-length π-spacers affecting the photo-to-electric conversion efficiency (PCE). Investigations are firstly performed on three porphyrin sensitizers with 1-3 conjugated phenylethynyl (PE) units, which have experimentally proved that the efficiency of power conversion decreases systematically with increasing spacer length. The distances and amounts of charge transfer after photoexcitation are calculated. In the PE bridged porphyrin dyes, the calculated electron injection driving forces and the regeneration driving forces gradually decrease as the distance of the π-spacer increases. Our theoretical calculations can reproduce well the experimental conclusion, showing that the photo-to-electric efficiency has a strong distance dependence for the electron-rich phenyl spacer. Then we replace the phenyl group with a pyrimidyl (PM) group to uncover how the characteristics of the π-spacer affect the performance of optical absorption, charge separation, and the regeneration process, to further improve the power conversion. We find that the adoption of electron-deficient pyrimidyl can break and even remove the distance dependence of the π-spacer. Some integral factors affecting the dye performance, such as short-circuit photocurrent, open-circuit voltage and charge collection efficiency are analyzed. It would help to interpret what role the electron deficient π-spacers with varied lengths will play and how they are expected to behave in the performance of sensitizers. In this regard, this study presents us with a promising way to design novel functional dyes and to utilize the potential advantages of the lengthy spacer dyes.
    Full-text · Article · Oct 2013 · RSC Advances
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    ABSTRACT: Ionization and dissociation of 2- and 3-methyl cyclopentanones have been investigated in molecular beams by their irradiation with intense 394 and 788 nm laser fields with pulse duration of 90 fs and intensity of 3 x 10(13)-4 x 10(14) W/cm(2). The analysis of the resulting mass spectra allowed us to discern the effects of methyl substitution and its position on the outcome of ionization/dissociation processes induced by the intense femtosecond laser field. Generalized Keldysh-Faisal-Reiss (g-KFR) and ab initio G3(MP2, CCSD)//B3LYP/6-31G*/RRKM theoretical calculations helped to uncover the formation mechanism of major ionic fragments observed in the mass spectra including C5H10+, C4H6O+, C3H3O+, C3H4O+, C3Hx+, and C2Hx+.
    Full-text · Article · Oct 2013 · Chemical Physics Letters

Publication Stats

2k Citations
396.63 Total Impact Points

Institutions

  • 2009-2015
    • National Chiao Tung University
      • Department of Applied Chemistry
      Hsin-chu-hsien, Taiwan, Taiwan
  • 1994-2014
    • Academia Sinica
      • Institute of Atomic and Molecular Sciences
      T’ai-pei, Taipei, Taiwan
  • 2008
    • National Dong Hwa University
      • Department of Chemistry
      Hualian, Taiwan, Taiwan
  • 2000-2008
    • National Taiwan University
      • Department of Chemistry
      T’ai-pei, Taipei, Taiwan
  • 2006
    • National Academy of Sciences of Ukraine
      Kievo, Kyiv City, Ukraine
  • 1997
    • Arizona State University
      • Department of Chemistry and Biochemistry
      Tempe, Arizona, United States