Sheng Hsien Lin

Academia Sinica, T’ai-pei, Taipei, Taiwan

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Publications (118)314.83 Total impact

  • [Show abstract] [Hide abstract]
    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.
    RSC Advances 10/2014; · 3.71 Impact Factor
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    ABSTRACT: 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.
    Rapid Communications in Mass Spectrometry 08/2014; 28(15):1716-22. · 2.51 Impact Factor
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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.
    The journal of physical chemistry. A. 06/2014;
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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.
    The Journal of chemical physics. 06/2014; 140(21):214108.
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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.
    Journal of Physical Chemistry Letters 05/2014; 5(11):2044–2049. · 6.59 Impact Factor
  • 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.
    The Journal of Physical Chemistry C. 11/2013; 117(45):23797–23805.
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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.
    The Journal of Chemical Physics 10/2013; 139(15):154302. · 3.12 Impact Factor
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    ABSTRACT: Recently the quantum chemistry program can provide the anharmonic potentials for polyatomic molecules and clusters. It makes the quantum calculation of intramlecular vibrational redistribution (IVR) rates and intramolecular vibrational energy transfer possible. In the present paper, we apply the adiabatic approximation method to treat these two intramolecular energy redistribution processes. Using this method, we calculate the IVR rates of the dipeptides (glycyl tyrosine (GlyTyr) and leucyl tyrosine (LeuTyr)) and their cation radicals from the high frequency modes to the low frequency modes. Our theoretical results of the IVR lifetimes of the high frequency modes, like C-H, N-H, and O-H stretching modes, for both GlyTyr and LeuTyr molecules and their cation radicals are about 1 ps, 10 ps, and 100 ps, respectively. It provides theoretical support for the claim that IVR takes place prior to dissociation and the IVR rates are determined by the functional group rather than the degrees of freedom of the system. Thus the Rice-Ramsperger-Kassel-Marcus (RRKM) theory is suitable for investigating the photodissociation process of dipeptides. In addition, the calculated intramolecular energy transfer rate from O-H stretching mode of the C-termius of dipeptides to N-H mode of N-terminus is close to IVR rate.
    Journal of the Chinese Chemical Society. 07/2013; 60(7).
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    ABSTRACT: The b-hairpin is a building block in the β-sheet structure. Understanding the formation of the β-hairpin may provide insight into the formation of β-sheet structures in, for example, protein amyloids. In this study, we performed molecular dynamics (MD) simulations to investigate the temperature-dependent transition behaviors of the GB1 β-hairpin peptide. The simulated results are analysed in terms of distances between pairs of peptide bonds and site-dependent dihedral angles. Our results show that the properties of the hairpin can be site-dependent and that the dependency is primarily associated with the hairpin's geometrical shape and specific interactions, such as hydrophobic clustering. Thus our study provides a foundation for the interpretation of probe-dependent experimental results.
    Journal of the Chinese Chemical Society. 07/2013; 60(7).
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    ABSTRACT: We investigate a Brownian pump which, being powered by a flashing ratchet mechanism, produces net particle transport through a membrane. The extension of the Parrondo's approach developed for reversible Brownian motors [Parrondo, Phys. Rev. E 57, 7297 (1998)] to adiabatically driven pumps is given. We demonstrate that the pumping mechanism becomes especially efficient when the time variation of the potential occurs adiabatically fast or adiabatically slow, in perfect analogy with adiabatically driven Brownian motors which exhibit high efficiency [Rozenbaum et al., Phys. Rev. E 85, 041116 (2012)]. At the same time, the efficiency of the pumping mechanism is shown to be less than that of Brownian motors due to fluctuations of the number of particles in the membrane.
    Physical Review E 07/2013; 88(1-1):012104. · 2.31 Impact Factor
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    ABSTRACT: The interactions between Ammoeng 100 and water are probed using high-pressure infrared measurements and DFT-calculations. The results of infrared absorption profiles suggest that the energetically favored approach for water molecules to interact with Ammoeng 100 is via the formation of anion-water interactions, whereas the alkyl C-H groups play much less important roles. After comparison with pure Ammoeng 100, it appears that no appreciable changes in band frequencies of alkyl C-H vibrations occurred as Ammoeng 100 was mixed with D2O. The presence of D2O has a red-shift effect on the peak frequency of the S[double bond, length as m-dash]O stretching vibration under the pressures below 1 GPa in comparison to the absorption frequencies of pure Ammoeng 100. This observation is likely related to local structures of the S[double bond, length as m-dash]O groups interacting with D2O molecules. DFT-calculations indicate that the most energetically favored conformation of ion pairs should be the species having only one hydrophilic hydrogen bonding. The results of calculations reveal that water addition may induce the partial replacement of C-HO interactions with strong hydrogen bonding between anions and water molecules.
    Physical Chemistry Chemical Physics 06/2013; · 4.20 Impact Factor
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    ABSTRACT: The water vapor fluorescence in air from filaments generated by intense ultrashort Ti:sapphire laser pulses is experimentally studied. The backscattered fluorescence from OH shows an exponential increase with increasing filament length, indicating amplified spontaneous emission. By measuring the intensity inside the filament and the fluorescence intensity of OH, a high degree of nonlinearity is obtained, indicating a highly nonlinear field dissociation of H2O molecule.
    Applied Physics Letters 06/2013; 102:224102. · 3.79 Impact Factor
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    ABSTRACT: The electronic and optical properties are studied using the density functional theory in (Si,Fe)-codoped anatase TiO2. The calculated results suggest that the synergistic effects of (Si,Fe) codoping can effectively induce the redshift of optical absorption edge, which leads to higher visible-light photocatalytic activity for hydrogen production by water splitting than pure anatase TiO2. To verify the reliability of our calculated results, nanocrystalline (Si,Fe)-codoped TiO2 is synthesized by a sol-gel-solvothermal method, and excellent absorption performance and photocatalytic activity for hydrogen production by water splitting are observed in our experiments.
    International Journal of Hydrogen Energy 05/2013; 38(13):5209–5214. · 3.55 Impact Factor
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    ABSTRACT: The electronic and optical properties of several possible C/B-codoped models of anatase and rutile TiO2 have been investigated systematically using spin-polarized density functional theory calculations. Our calculated results show that the synergistic effect of C/B codoping can induce some hybridized energy states appearing in the forbidden gap and the band gap has a narrowing in anatase and rutile TiO2, which can lead to a decrease of the photon excitation energy and an obvious red-shift of the optical absorption edge. These results lead to an excellent photocatalytic activity in C/B-codoped TiO2. Moreover, with the increase of C and B impurities’ concentration in anatase and rutile TiO2, we find that the intensity of impurity states has a strengthening in the band gap, the position of impurity states changes, and the visible-light absorption performance improves gradually.
    J. Mater. Chem. A. 03/2013; 1(14):4516-4524.
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    ABSTRACT: In this theoretical study, we aimed to simulate the sum-frequency generation (SFG) spectroscopy of a thin polystyrene layer physically adsorbed on the graphene sheet and to figure out the orientation distribution of the phenyl units. To simplify the problem, we started the investigation by constructing molecular models with styrene and ethylbenzene monomers and styrene oligomers up to four units adsorbed on a finite-sized graphene hexagon. Geometric optimization results showed that the phenyl rings of the adsorbate always orientate close to the surface normal with a small tilt angle. The adsorption is weak but not negligible. SFG spectra have been simulated based on these calculated structures, vibrational frequencies, and dipole and polarizability derivatives to compare with experimental reports of polystyrene adsorbed on other surfaces.
    The Journal of Physical Chemistry C. 01/2013; 117(4):1754–1760.
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    ABSTRACT: In the present letter we investigate the noncovalent interactions in the mixed coaggregates of 1,3,5-triphenyl-2-pyrazoline (TPP) and 1,4-dicyanonaphthalene (DCN) and their influence on the excited-state properties of the TPP–DCN. The theoretical results show that the π–π stacking interactions play an important role in the noncovalent interactions of the TPP–DCN coaggregates. The effect of the π–π interactions on the excited-state properties of the TPP–DCN is also fully investigated, and the results indicate that the TPP and DCN do not form an intermolecular charge-transfer complex in the ground state, whereas they form an exciplex in the excited state.
    Chemical Physics Letters 01/2013; 556:230–236. · 2.15 Impact Factor
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    ABSTRACT: Instantaneous (laser field-dependent) potential energy curves leading to neutral fragmentations of methane were calculated at several points of laser intensities of to ( to V/m) by using ab initio molecular orbital (MO) methods to validate the observation of neutral fragmentations induced by intense femtosecond IR pulses [Kong et al., J. Chem. Phys.125 (2006) 133320]. Two fragmentation paths, CH2 + 2H and , in 1T2 superexcited states that are located in energy ranges of 12~16 eV were considered as the reaction paths since these states are responsible for Jahn-Teller to open up reaction paths during ultrashort pulses. As field intensity increased, the low-lying excited 1A1 states originated from the Jahn-Teller 1T2 states were substantially stabilized along the neutral fragment path and were located below the ionization threshold. On the other hand, the low-lying excited 1B1 states, which are also originated from the Jahn-Teller 1T2 states, were embedded on the ionized state along the dissociation path to . This indicates that ionic fragments, rather than neutral ones, are produced along the path. The computational results support neutral fragmentations via superexcited states proposed by Kong et al.
    The Journal of Physical Chemistry A 12/2012; · 2.77 Impact Factor
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    ABSTRACT: Herein, we propose a modified version of the Wako-Saitô-Muñoz-Eaton (WSME) model. The proposed model introduces an empirical temperature parameter for the hypothetical structural units (i.e., foldons) in proteins to include site-dependent thermodynamic behavior. The thermodynamics for both our proposed model and the original WSME model were investigated. For a system with beta-hairpin topology, a mathematical treatment (contact-pair treatment) to facilitate the calculation of its partition function was developed. The results show that the proposed model provides better insight into the site-dependent thermodynamic behavior of the system, compared with the original WSME model. From this site-dependent point of view, the relationship between probe-dependent experimental results and model’s thermodynamic predictions can be explained. The model allows for suggesting a general principle to identify foldon behavior. We also find that the backbone hydrogen bonds may play a role of structural constraints in modulating the cooperative system. Thus, our study may contribute to the understanding of the fundamental principles for the thermodynamics of protein folding.
    Journal of Biological Physics 09/2012; 38(4). · 0.95 Impact Factor
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    ABSTRACT: Nonplanar chiral aromatic molecules are candidates for use as building blocks of multidimensional switching devices because the π electrons can generate ring currents with a variety of directions. We employed (P)-2,2'-biphenol because four patterns of π-electron rotations along the two phenol rings are possible and theoretically determine how quantum switching of the π-electron rotations can be realized. We found that each rotational pattern can be driven by a coherent excitation of two electronic states under two conditions: one is the symmetry of the electronic states and the other is their relative phase. On the basis of the results of quantum dynamics simulations, we propose a quantum control method for sequential switching among the four rotational patterns that can be performed by using ultrashort overlapped pump and dump pulses with properly selected relative phases and photon polarization directions. The results serve as a theoretical basis for the design of confined ultrafast switching of ring currents of nonplanar molecules and further current-induced magnetic fluxes of more sophisticated systems.
    Journal of the American Chemical Society 08/2012; 134(35):14279-82. · 10.68 Impact Factor
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    ABSTRACT: This investigation concerns the initial chemical reactions that affect the ionization of matrixes in matrix-assisted laser desorption/ionization (MALDI). The study focuses on the relaxations of photon energy that occur on a comparable time scale to that of ionization, in which the available laser energy is shared and the ionization condition is changed. The relaxations include fluorescence, fragmentation, and nonradiative relaxation from the excited state to the ground state. With high absorption cross section and long excited-state lifetime, photoionization of matrix plays an important role if sufficient laser energy is used. Under other conditions, thermal ionization of the molecule in the ground state is predicted to be one of the important reactions. Evidence of change in the branching ratio of initial reactions with the matrix and the excitation wavelength was obtained with α-cyano-4-hydroxycinnamic acid, sinapinic acid, 2,5-dihydroxybenzoic acid, and 2,4,6-trihydroxyacetophenone. These matrixes are studied by obtaining their mixed crystal absorption spectra, fluorescence properties, laser-induced infrared emission, and product ions. The exact ionization pathway depends on the chemical properties of matrixes and the excitation conditions. This concept may explain the diversity of experimental results observed in MALDI experiments, which provides an insight into the ensemble of chemical reactions that govern the generation of ions.
    The Journal of Physical Chemistry B 07/2012; 116(32):9635-43. · 3.61 Impact Factor

Publication Stats

409 Citations
314.83 Total Impact Points

Institutions

  • 1996–2014
    • Academia Sinica
      • • Institute of Atomic and Molecular Sciences
      • • Research Center for Applied Sciences
      T’ai-pei, Taipei, Taiwan
  • 2006–2013
    • National Dong Hwa University
      • Department of Chemistry
      Hualian, Taiwan, Taiwan
    • National Chiao Tung University
      • Department of Applied Chemistry
      Hsin-chu-hsien, Taiwan, Taiwan
    • National Tsing Hua University
      • Department of Chemistry
      Hsin-chu-hsien, Taiwan, Taiwan
    • Sejong University
      Sŏul, Seoul, South Korea
  • 2011–2012
    • Southwest University in Chongqing
      • School of Chemistry and Chemical Engineering
      Chongqing, Chongqing Shi, China
    • National Taiwan University of Science and Technology
      • Department of Chemical Engineering
      Taipei, Taipei, Taiwan
  • 2010
    • Sichuan University
      • College of Chemical Engineering
      Chengdu, Sichuan Sheng, China
  • 2009
    • Kyoto University
      • Division of Chemistry
      Kyoto, Kyoto-fu, Japan
    • Kyushu University
      • Faculty of Sciences
      Fukuoka-shi, Fukuoka-ken, Japan
  • 2000–2008
    • National Taiwan University
      • Department of Chemistry
      T’ai-pei, Taipei, Taiwan
  • 2007
    • Technische Universität München
      München, Bavaria, Germany
  • 1994
    • Arizona State University
      Phoenix, Arizona, United States