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Li, J., Luo, Y. & Zhang, J. (2018). A theoretical study on vibronic spectra and photo conversation process of protonated naphthalenes. Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, 205, 520-527
Open this publication in new window or tab >>A theoretical study on vibronic spectra and photo conversation process of protonated naphthalenes
2018 (English)In: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy, ISSN 1386-1425, E-ISSN 1873-3557, Vol. 205, p. 520-527Article in journal (Refereed) Published
Abstract [en]

The equilibrium structures and vibrational frequencies of the ground state and several singlet low-lying excited states of alpha-and beta-protonated naphthalenes (alpha-and beta-HN+) have been studied by time -dependent density -functional theory (TD-DFT). Within the Franck -Condon approximation, vibronic absorption spectra of alpha-HN+ and beta-HN+, together with the vibronic emission spectrum of alpha-HN+, have been calculated. The obtained good agreement between the theoretical and experimental spectra enables to correctly assign vibronic features in both absorption and emission spectra. Moreover, the non -radiative deactivation pathway from the low-lying excite states to the ground state in alpha-HN+ and beta-HN+, as well as the photo-induce proton transfer pathway, are investigated at the CASPT2/CASSCF/6-31G* level. Our study is helpful for understanding the photochemical behavior of these important polycyclic aromatic hydrocarbon molecules.

Place, publisher, year, edition, pages
Pergamon Press, 2018
Keywords
Vibronic spectra, Photo conversation, Theoretical study, Protonated naphthalenes
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-235992 (URN)10.1016/j.saa.2018.07.074 (DOI)000445713600061 ()30071500 (PubMedID)2-s2.0-85050638025 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20181015

Available from: 2018-10-15 Created: 2018-10-15 Last updated: 2019-01-18Bibliographically approved
Xie, Z., Duan, S., Tian, G., Wang, C.-K. & Luo, Y. (2018). Theoretical modeling of tip-enhanced resonance Raman images of switchable azobenzene molecules on Au(111). Nanoscale, 10(25), 11850-11860
Open this publication in new window or tab >>Theoretical modeling of tip-enhanced resonance Raman images of switchable azobenzene molecules on Au(111)
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2018 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 25, p. 11850-11860Article in journal (Refereed) Published
Abstract [en]

With a highly localized plasmonic field, tip-enhanced Raman spectroscopy (TERS) images have reached atomic-scale resolution, providing an optical means to explore the structure of a single molecule. We have applied the recently developed theoretical method to simulate the TERS images of trans and cis azobenzene as well as its derivatives on Au(111). Our theoretical results reveal that when the first excited state is resonantly excited, TERS images from a highly confined plasmonic field can effectively distinguish the isomer configurations of the adsorbates. The decay of the plasmonic field along the surface normal can be further used to distinguish different nonplanar cis configurations. Moreover, subtle characteristics of different molecular configurations can also be identified from the TERS images of other resonant excited states with a super-high confined plasmonic field. These findings serve as good references for future TERS experiments on molecular isomers.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-232390 (URN)10.1039/c8nr01988f (DOI)000437761500015 ()29897090 (PubMedID)2-s2.0-85049505191 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20180727

Available from: 2018-07-27 Created: 2018-07-27 Last updated: 2018-07-27Bibliographically approved
Liu, J., Ji, Y., Nai, J., Niu, X., Luo, Y., Guo, L. & Yang, S. (2018). Ultrathin amorphous cobalt-vanadium hydr(oxy)oxide catalysts for the oxygen evolution reaction. Energy & Environmental Science, 11(7), 1736-1741
Open this publication in new window or tab >>Ultrathin amorphous cobalt-vanadium hydr(oxy)oxide catalysts for the oxygen evolution reaction
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2018 (English)In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 11, no 7, p. 1736-1741Article in journal (Refereed) Published
Abstract [en]

Cost efficient and long-term stable catalysts are in great demand for the oxygen evolution reaction (OER), a key process involved in water splitting cells and metal-air batteries. Here, we demonstrate that the ultrathin amorphous cobalt-vanadium hydr(oxy)oxide we synthesized is a highly promising electrocatalytic material for the OER with a low overpotential of 0.250 V (even lower down to 0.215 V when supported on Au foam) at 10 mA cm(-2) and a long stable operation time (170 h) in alkaline media. In combination with in situ X-ray absorption spectral characterization and first-principles simulations, we reveal that the ultrathin, amorphous and alloyed structural characteristics have enabled its facile transformation to the desirable active phase, leading to a dramatically enhanced catalytic activity. Our finding highlights the remarkable advantages of the two-dimensional amorphous material and sheds new light on the design of high-performance electrocatalysts.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-232621 (URN)10.1039/c8ee00611c (DOI)000438392400008 ()2-s2.0-85050152583 (Scopus ID)
Note

QC 20180730

Available from: 2018-07-30 Created: 2018-07-30 Last updated: 2018-07-30Bibliographically approved
Tan, S., Feng, H., Ji, Y., Zheng, Q., Shi, Y., Zhao, J., . . . Hou, J. G. (2018). Visualizing Elementary Reactions of Methanol by Electrons and Holes on TiO2(110) Surface. The Journal of Physical Chemistry C, 122(50), 28805-28814
Open this publication in new window or tab >>Visualizing Elementary Reactions of Methanol by Electrons and Holes on TiO2(110) Surface
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2018 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 50, p. 28805-28814Article in journal (Refereed) Published
Abstract [en]

Direct visualization and comparison of the elementary reactions induced by electrons and holes are of importance for finding a way to conduct chemical reactions and reaction sequences in a controllable manner. As a semiconductor, TiO2 provides a playground to perform the measurements, and moreover, the information can be useful for design of high-performance TiO2-based catalysts and photocatalysts. Here, we present our investigation on the elementary reactions of CH3OH on TiO2 surface through visualization of specific elementary steps by highly controllable electron and hole injection using scanning tunneling microscopy. The distinct sequential routes and their kinetics, namely, breaking C-O and O-H bonds by electrons and breaking O-H and C-H bonds by holes, respectively, have been experimentally identified and well elucidated by density functional theory calculations. Our nonlocal h-injection experimental and theoretical results suggest that the delocalized holes in the TiO2 substrate should be responsible for the temperature-dependent h-route reactions. The locally triggered e-route reaction is associated with the fact that the location of the unoccupied hybridization states is much higher than that of the conduction band onset. Our findings resolve the long-standing debate about the intermediate species and reaction mechanism in photocatalytic oxidation of CH3OH. Our proposed protocol offers a powerful means to study elementary reactions induced by electrons and holes on a semiconductor surface in general.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-241328 (URN)10.1021/acs.jpcc.8b09784 (DOI)000454566700036 ()2-s2.0-85058525958 (Scopus ID)
Note

QC 20190123

Available from: 2019-01-23 Created: 2019-01-23 Last updated: 2019-01-23Bibliographically approved
Zhang, R., Zhang, X., Wang, H., Zhang, Y., Jiang, S., Hu, C., . . . Dong, Z. (2017). Distinguishing Individual DNA Bases in a Network by Non-Resonant Tip-Enhanced Raman Scattering. Angewandte Chemie International Edition, 56(20), 5561-5564
Open this publication in new window or tab >>Distinguishing Individual DNA Bases in a Network by Non-Resonant Tip-Enhanced Raman Scattering
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2017 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, no 20, p. 5561-5564Article in journal (Refereed) Published
Abstract [en]

The importance of identifying DNA bases at the single-molecule level is well recognized for many biological applications. Although such identification can be achieved by electrical measurements using special setups, it is still not possible to identify single bases in real space by optical means owing to the diffraction limit. Herein, we demonstrate the outstanding ability of scanning tunneling microscope (STM)-controlled non-resonant tip-enhanced Raman scattering (TERS) to unambiguously distinguish two individual complementary DNA bases (adenine and thymine) with a spatial resolution down to 0.9 nm. The distinct Raman fingerprints identified for the two molecules allow to differentiate in real space individual DNA bases in coupled base pairs. The demonstrated ability of non-resonant Raman scattering with super-high spatial resolution will significantly extend the applicability of TERS, opening up new routes for singlemolecule DNA sequencing.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2017
Keywords
DNA bases, molecular recognition, non-resonant Raman spectroscopy, scanning tunneling microscopy, tip-enhanced Raman scattering
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-207657 (URN)10.1002/anie.201702263 (DOI)000400458700027 ()28394094 (PubMedID)2-s2.0-85017444809 (Scopus ID)
Note

QC 20170602

Available from: 2017-06-02 Created: 2017-06-02 Last updated: 2017-06-02Bibliographically approved
Li, H., Jiang, J. & Luo, Y. (2017). Identification of the protonation site of gaseous triglycine: the cis-peptide bond conformation as the global minimum. Physical Chemistry, Chemical Physics - PCCP, 19(23), 15030-15038
Open this publication in new window or tab >>Identification of the protonation site of gaseous triglycine: the cis-peptide bond conformation as the global minimum
2017 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 23, p. 15030-15038Article in journal (Refereed) Published
Abstract [en]

Extensive ab initio investigations have been performed to characterize stable conformers of protonated triglycine (GGGH) in the gas phase. Calculations using the composite CBS-QB3 method confirmed that the most favorable site of protonation on triglycine at 298 K is still the traditional amino nitrogen, rather than the more-recently reported amide oxygen. Furthermore, a non-proline cis-peptide bond conformer is identified for the first time as the global minimum of GGGH. Further transition state calculations considering the temperature effects explained why the previous experimental infrared multiple photon dissociation (IRMPD) spectrum contains a combination of two local minima, rather than a global one. First-principles simulations have been performed for near-edge X-ray absorption fine-structure (NEXAFS) spectra and X-ray photoelectron spectra (XPS) at the C, N and O K-edges to identify the notable spectral differences that enable the unambiguous identification of different protonated forms. The calculated proton affinity (PA) and gas basicity (GB) of triglycine are in excellent agreement with the experimental values. Our study thus provides valuable insights into the protonation of short peptides and illustrates the competition between cis and trans peptide bonds.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-211014 (URN)10.1039/c7cp01997a (DOI)000403561200017 ()28555233 (PubMedID)
Note

QC 20170712

Available from: 2017-07-12 Created: 2017-07-12 Last updated: 2017-07-12Bibliographically approved
Hu, W., Duan, S., Zhang, Y., Ren, H., Jiang, J. & Luo, Y. (2017). Identifying the structure of 4-chlorophenyl isocyanide adsorbed on Au(111) and Pt(111) surfaces by first-principles simulations of Raman spectra. Physical Chemistry, Chemical Physics - PCCP, 19(48), 32389-32397
Open this publication in new window or tab >>Identifying the structure of 4-chlorophenyl isocyanide adsorbed on Au(111) and Pt(111) surfaces by first-principles simulations of Raman spectra
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2017 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 48, p. 32389-32397Article in journal (Refereed) Published
Abstract [en]

Surface Raman spectroscopy has become one of the most powerful analytical tools for interfacial structures. However, theoretical modeling for the Raman spectra of molecular adsorbate on metallic surfaces is a long-standing challenge because accurate descriptions of the electronic structure for both the metallic substrates and adsorbates are required. Here we present a quasi-analytical method for high-precision surface Raman spectra at the first principle level. Using this method, we correlate both geometrical and electronic structures of a single 4-chlorophenyl isocyanide (CPI) molecule adsorbed on a Au(111) or Pt(111) surface with its Raman spectra. The "finger-print'' frequency shift of the CN stretching mode reveals the in situ configuration of CPI is vertical adsorption on the top site of the Au(111) surface, but a bent configuration when it adsorbs on the hollow site of the Pt(111) surface. Electronic structure calculations reveal that a pi-back donation mechanism often causes a red shift to the Raman response of CN stretching mode. In contrast, sigma donation as well as a wall effect introduces a blue shift to the CN stretching mode. A clear relationship for the dependence of Raman spectra on the surface electronic and geometrical information is built up, which largely benefits the understanding of chemical and physical changes during the adsorption. Our results highlight that high-precision theoretical simulations are essential for identifying in situ geometrical and electronic surface structures.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-220592 (URN)10.1039/c7cp06329f (DOI)000417958900021 ()29185564 (PubMedID)2-s2.0-85038415164 (Scopus ID)
Note

QC 20180117

Available from: 2018-01-17 Created: 2018-01-17 Last updated: 2018-03-12Bibliographically approved
Xie, Z., Duan, S., Wang, C.-K. & Luo, Y. (2017). Lighting up long-range charge-transfer states by a localized plasmonic field. Nanoscale, 9(46), 18189-18193
Open this publication in new window or tab >>Lighting up long-range charge-transfer states by a localized plasmonic field
2017 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 46, p. 18189-18193Article in journal (Refereed) Published
Abstract [en]

The long-range charge-transfer states in a donor-acceptor system exhibit well separated electron-hole pairs, but are often difficult to achieve by optical means owing to a very small overlap between the wave functions of the donor and acceptor. We have found that the introduction of a spatially confined plasmon can enhance the transition probability to the long-range charge-transfer states as it can effectively break the intrinsic symmetry selection rule imposed on the system. Meanwhile, the intensity borrowed from local excitations could also be selectively promoted, allowing the manipulation of the excited quantum states. In addition, our calculations reveal that the donor and acceptor moieties can be unambiguously visualized in real space by tip-enhanced resonance Raman images. These findings can benefit light-harvesting and also be readily extended to diverse optical processes.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
National Category
Theoretical Chemistry Biological Sciences
Identifiers
urn:nbn:se:kth:diva-220454 (URN)10.1039/c7nr06322a (DOI)000416824100006 ()2-s2.0-85036465256 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20180103

Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-01-03Bibliographically approved
Hu, W., Duan, S. & Luo, Y. (2017). Theoretical modeling of surface and tip-enhanced Raman spectroscopies. Wiley Interdisciplinary Reviews. Computational Molecular Science, 7(2), Article ID UNSP e1293.
Open this publication in new window or tab >>Theoretical modeling of surface and tip-enhanced Raman spectroscopies
2017 (English)In: Wiley Interdisciplinary Reviews. Computational Molecular Science, ISSN 1759-0876, E-ISSN 1759-0884, Vol. 7, no 2, article id UNSP e1293Article, review/survey (Refereed) Published
Abstract [en]

Raman spectroscopy is a powerful technique in molecular science because of the ability of providing vibrational 'finger-print'. The developments of the surfaceenhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) have significantly improved the detection sensitivity and efficiency. However, they also introduce complications for the spectral assignments, for which advanced theoretical modeling has played an important role. Here we summarize some of our recent progresses for SERS and TERS, which generally combine both solid-state physics and quantum chemistry methods with two different schemes, namely the cluster model and the periodic boundary condition (PBC) model. In the cluster model, direct Raman spectra calculations are performed for the cluster taken from the accurate PBC structure. For PBC model, we have developed a quasianalytical approach that enables us to calculate the Raman spectra of entire system. Under the TERS condition, the non-uniformity of plasmonic field in real space can drastically alter the interaction between the molecule and the light. By taking into account the local distributions of the plasmonic field, a new interaction Hamiltonian is constructed and applied to model the super-high-resolution Raman images of a single molecule. It shows that the resonant Raman images reflect the transition density between ground and excited states, which are generally vibrational insensitive. The nonresonant Raman images, on the other hand, allow to visualize the atomic movement of individual vibrational modes in real space. The inclusion of non-uniformity of plasmonic field provides ample opportunities to discover new physics and new applications in the future. 

Place, publisher, year, edition, pages
WILEY, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-206709 (URN)10.1002/wcms.1293 (DOI)000399013100003 ()2-s2.0-85007367855 (Scopus ID)
Note

QC 20170508

Available from: 2017-05-08 Created: 2017-05-08 Last updated: 2017-05-08Bibliographically approved
Liu, L., Li, X.-F., Yan, Q., Li, Q.-K., Zhang, X.-H., Deng, M., . . . Luo, Y. (2017). Uniform and perfectly linear current-voltage characteristics of nitrogen-doped armchair graphene nanoribbons for nanowires. Physical Chemistry, Chemical Physics - PCCP, 19(1), 44-48
Open this publication in new window or tab >>Uniform and perfectly linear current-voltage characteristics of nitrogen-doped armchair graphene nanoribbons for nanowires
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2017 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 1, p. 44-48Article in journal (Refereed) Published
Abstract [en]

Metallic nanowires with desired properties for molecular integrated circuits (MICs) are especially significant in molectronics, but preparing such wires at a molecular level still remains challenging. Here, we propose, from first principles calculations, experimentally realizable edge-nitrogen-doped graphene nanoribbons (N-GNRs) as promising candidates for nanowires. Our results show that edge N-doping has distinct effects on the electronic structures and transport properties of the armchair GNRs and zigzag GNRs (AGNRs, ZGNRs), due to the formation of pyridazine and pyrazole rings at the edges. The pyridazine rings raise the Fermi level and introduce delocalized energy bands near the Fermi level, resulting in a highly enhanced conductance in N-AGNRs at the stable nonmagnetic ground state. Especially for the family of AGNRs with widths of n = 3p + 2, their semiconducting characteristics are transformed to metallic characteristics via N-doping, and they exhibit perfectly linear current-voltage (I-V) behaviors. Such uniform and excellent features indicate bright application prospects of the N-AGNRs as nanowires and electrodes in molectronics.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-201247 (URN)10.1039/c6cp06640b (DOI)000391725300002 ()
Note

QC 20170215

Available from: 2017-02-15 Created: 2017-02-15 Last updated: 2017-11-29Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-0007-0394

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