76
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Wagner SR, Huang B, Park C, Feng J, Yoon M, Zhang P. Growth of Metal Phthalocyanine on Deactivated Semiconducting Surfaces Steered by Selective Orbital Coupling. PHYSICAL REVIEW LETTERS 2015; 115:096101. [PMID: 26371664 DOI: 10.1103/physrevlett.115.096101] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Indexed: 05/20/2023]
Abstract
Using scanning tunneling microscopy and density functional theory, we show that the molecular ordering and orientation of metal phthalocyanine molecules on the deactivated Si surface display a strong dependency on the central transition-metal ion, driven by the degree of orbital hybridization at the heterointerface via selective p-d orbital coupling. This Letter identifies a selective mechanism for modifying the molecule-substrate interaction which impacts the growth behavior of transition-metal-incorporated organic molecules on a technologically relevant substrate for silicon-based devices.
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77
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Li X, Basile L, Huang B, Ma C, Lee J, Vlassiouk IV, Puretzky AA, Lin MW, Yoon M, Chi M, Idrobo JC, Rouleau CM, Sumpter BG, Geohegan DB, Xiao K. Van der Waals Epitaxial Growth of Two-Dimensional Single-Crystalline GaSe Domains on Graphene. ACS NANO 2015; 9:8078-8088. [PMID: 26202730 DOI: 10.1021/acsnano.5b01943] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Two-dimensional (2D) van der Waals (vdW) heterostructures are a family of artificially structured materials that promise tunable optoelectronic properties for devices with enhanced functionalities. Compared to transferring, direct epitaxy of vdW heterostructures is ideal for clean interlayer interfaces and scalable device fabrication. Here we report the synthesis and preferred orientations of 2D GaSe atomic layers on graphene (Gr) by vdW epitaxy. GaSe crystals are found to nucleate predominantly on random wrinkles or grain boundaries of graphene, share a preferred lattice orientation with underlying graphene, and grow into large (tens of micrometers) irregularly shaped, single-crystalline domains. The domains are found to propagate with triangular edges that merge into the large single crystals during growth. Electron diffraction reveals that approximately 50% of the GaSe domains are oriented with a 10.5 ± 0.3° interlayer rotation with respect to the underlying graphene. Theoretical investigations of interlayer energetics reveal that a 10.9° interlayer rotation is the most energetically preferred vdW heterostructure. In addition, strong charge transfer in these GaSe/Gr vdW heterostructures is predicted, which agrees with the observed enhancement in the Raman E(2)1g band of monolayer GaSe and highly quenched photoluminescence compared to GaSe/SiO2. Despite the very large lattice mismatch of GaSe/Gr through vdW epitaxy, the predominant orientation control and convergent formation of large single-crystal flakes demonstrated here is promising for the scalable synthesis of large-area vdW heterostructures for the development of new optical and optoelectronic devices.
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78
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Tian YH, Huang J, Sheng X, Sumpter BG, Yoon M, Kertesz M. Nitrogen Doping Enables Covalent-Like π-π Bonding between Graphenes. NANO LETTERS 2015; 15:5482-91. [PMID: 26151153 DOI: 10.1021/acs.nanolett.5b01940] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The neighboring layers in bilayer (and few-layer) graphenes of both AA and AB stacking motifs are known to be separated at a distance corresponding to van der Waals (vdW) interactions. In this Letter, we present for the first time a new aspect of graphene chemistry in terms of a special chemical bonding between the giant graphene "molecules". Through rigorous theoretical calculations, we demonstrate that the N-doped graphenes (NGPs) with various doping levels can form an unusual two-dimensional (2D) π-π bonding in bilayer NGPs bringing the neighboring NGPs to significantly reduced interlayer separations. The interlayer binding energies can be enhanced by up to 50% compared to the pristine graphene bilayers that are characterized by only vdW interactions. Such an unusual chemical bonding arises from the π-π overlap across the vdW gap while the individual layers maintain their in-plane π-conjugation and are accordingly planar. The existence of the resulting interlayer covalent-like bonding is corroborated by electronic structure calculations and crystal orbital overlap population (COOP) analyses. In NGP-based graphite with the optimal doping level, the NGP layers are uniformly stacked and the 3D bulk exhibits metallic characteristics both in the in-plane and along the stacking directions.
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79
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Park C, Ryou J, Hong S, Sumpter BG, Kim G, Yoon M. Electronic Properties of Bilayer Graphene Strongly Coupled to Interlayer Stacking and an External Electric Field. PHYSICAL REVIEW LETTERS 2015; 115:015502. [PMID: 26182105 DOI: 10.1103/physrevlett.115.015502] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Indexed: 06/04/2023]
Abstract
Bilayer graphene (BLG) with a tunable band gap appears interesting as an alternative to graphene for practical applications; thus, its transport properties are being actively pursued. Using density functional theory and perturbation analysis, we investigated, under an external electric field, the electronic properties of BLG in various stackings relevant to recently observed complex structures. We established the first phase diagram summarizing the stacking-dependent gap openings of BLG for a given field. We further identified high-density midgap states, localized on grain boundaries, even under a strong field, which can considerably reduce the overall transport gap.
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80
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Koo J, Yoon M, Chung W, Kim D. SU-E-T-617: Plan Quality Estimation of Intensity-Modulated Radiotherapy Cases for Lung Cancer. Med Phys 2015. [DOI: 10.1118/1.4924980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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81
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Jeong S, Kim D, Chung W, Yoon M, Shin D, Chung M. SU-E-T-801: Verification of Dose Information Passed Through 3D-Printed Products. Med Phys 2015. [DOI: 10.1118/1.4925165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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82
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Son J, Kim M, Hwang U, Park J, Lim Y, Lee S, Park S, Yoon M, Shin D. SU-E-T-159: Characteristics of Fiber-Optic Radiation Sensor for Proton Therapeutic Beam. Med Phys 2015. [DOI: 10.1118/1.4924521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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83
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Moon S, Kim D, Chung W, Yoon M. SU-E-T-449: Hippocampal Sparing Radiotherapy Using Intensity Modulated Radiotherapy and Volumetric Modulated Arc Therapy. Med Phys 2015. [DOI: 10.1118/1.4924811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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84
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Kim D, Han E, Paudel N, Hardee M, Chung W, Sung J, Yoon M. SU-E-T-728: The Comparison of Risk of Secondary Malignancies Arising From Five Different Whole Breast Radiation Treatments. Med Phys 2015. [DOI: 10.1118/1.4925092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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85
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Li X, Basile L, Yoon M, Ma C, Puretzky AA, Lee J, Idrobo JC, Chi M, Rouleau CM, Geohegan DB, Xiao K. Revealing the Preferred Interlayer Orientations and Stackings of Two-Dimensional Bilayer Gallium Selenide Crystals. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201409743] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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86
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Li X, Basile L, Yoon M, Ma C, Puretzky AA, Lee J, Idrobo JC, Chi M, Rouleau CM, Geohegan DB, Xiao K. Revealing the Preferred Interlayer Orientations and Stackings of Two-Dimensional Bilayer Gallium Selenide Crystals. Angew Chem Int Ed Engl 2015; 54:2712-7. [DOI: 10.1002/anie.201409743] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Indexed: 11/08/2022]
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87
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Ganesh P, Kim J, Park C, Yoon M, Reboredo FA, Kent PRC. Binding and Diffusion of Lithium in Graphite: Quantum Monte Carlo Benchmarks and Validation of van der Waals Density Functional Methods. J Chem Theory Comput 2014; 10:5318-23. [DOI: 10.1021/ct500617z] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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88
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Park J, Lee J, Liu L, Clark KW, Durand C, Park C, Sumpter BG, Baddorf AP, Mohsin A, Yoon M, Gu G, Li AP. Spatially resolved one-dimensional boundary states in graphene-hexagonal boron nitride planar heterostructures. Nat Commun 2014; 5:5403. [PMID: 25377633 DOI: 10.1038/ncomms6403] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/29/2014] [Indexed: 11/09/2022] Open
Abstract
Two-dimensional interfaces between crystalline materials have been shown to generate unusual interfacial electronic states in complex oxides. Recently, a one-dimensional interface has been realized in hexagonal boron nitride and graphene planar heterostructures, where a polar-on-nonpolar one-dimensional boundary is expected to possess peculiar electronic states associated with edge states of graphene and the polarity of boron nitride. Here we present a combined scanning tunnelling microscopy and first-principles theory study of the graphene-boron nitride boundary to provide a first glimpse into the spatial and energetic distributions of the one-dimensional boundary states down to atomic resolution. The revealed boundary states are about 0.6 eV below or above the Fermi level depending on the termination of the boron nitride at the boundary, and are extended along but localized at the boundary. These results suggest that unconventional physical effects similar to those observed at two-dimensional interfaces can also exist in lower dimensions.
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89
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Yoon M, Huterer D, Gibelyou C, Kovacs A, Szapudi I. Dipolar modulation in number counts of WISE-2MASS sources. ACTA ACUST UNITED AC 2014. [DOI: 10.1093/mnrasl/slu133] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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90
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Ahn S, Na K, Kim Y, Kim K, Oh I, Song S, Chung W, Nam T, Song J, Yoon M, Jeong J, Kim Y. Surgical Salvation After Full-Dose Concurrent Chemoradiation in Patients With Locally Advanced Non-Small Cell Lung Cancer (NSCLC). Int J Radiat Oncol Biol Phys 2014. [DOI: 10.1016/j.ijrobp.2014.05.1845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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91
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Son J, Kim M, Shin D, Yoon M, Hwang U. Development of Proton Dosimetry System Using Fiber-Optic Array Including Real-Time Analysis Software Tool. Int J Radiat Oncol Biol Phys 2014. [DOI: 10.1016/j.ijrobp.2014.05.2611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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92
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Son J, Kim M, Shin D, Lim Y, Lee S, Kim J, Hwang U, Kim J, Yoon M. SU-E-T-111: Development of Proton Dosimetry System Using Fiber-Optic Cerenkov Radiation Sensor Array. Med Phys 2014. [DOI: 10.1118/1.4888441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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93
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Song J, Yoon M, Nam T, Ahn S, Chung W. SU-E-T-163: Evaluation of Dose Distributions Recalculated with Per-Field Measurement Data Under the Condition of Respiratory Motion During IMRT for Liver Cancer. Med Phys 2014. [DOI: 10.1118/1.4888492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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94
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Lee H, Kim D, Chung W, Sung J, Yoon M. SU-E-T-322: The Evaluation of the Gafchromic EBT3 Film in Low Dose 6 MV X-Ray Beams with Different Scanning Modes. Med Phys 2014. [DOI: 10.1118/1.4888655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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95
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Kim D, Chung W, Shin D, Yoon M. SU-E-T-208: Incidence Cancer Risk From the Radiation Treatment for Acoustic Neuroma Patient. Med Phys 2014. [DOI: 10.1118/1.4888538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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96
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Sung J, Kim D, Kim D, Baek T, Lee H, Chung W, Yoon M. SU-E-T-306: Study of the Reduction Technique for the Secondary Cancer Risk Due to Cone Beam CT in Image Guided Radiotherapy. Med Phys 2014. [DOI: 10.1118/1.4888638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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97
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Baek T, Chung E, Lee S, Yoon M. SU-E-T-335: Transit Dosimetry for Verification of Dose Delivery Using Electronic Portal Imaging Device (EPID). Med Phys 2014. [DOI: 10.1118/1.4888668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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98
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Kim D, Chung W, Bae S, Park S, Lee H, Sung J, Yoon M. EP-1792: Comparison of the organ equivalent dose from the scattered radiation of aucostic schwannoma. Radiother Oncol 2014. [DOI: 10.1016/s0167-8140(15)31910-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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99
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Yoon M, Burrow MF, Wong R, Parashos P. Effect of Sodium Ascorbate on Resin Bonding to Sodium Perborate–bleached Dentin. Oper Dent 2014; 39:98-106. [DOI: 10.2341/12-516-l] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
SUMMARY
This was an in vitro study to evaluate the effect of sodium ascorbate on the microshear bond strength (MSBS) of resin composite to sodium perborate–bleached dentin. Molar dentin sections were divided into six groups: 1) control, 2) sodium perborate (SP) bleach and immediate bonding, 3) SP and 30 second sodium ascorbate (SA); 4) SP and 1 minute SA; 5) SP and 2 minute SA; and 6) SP and 7 day delay before bonding. They were further divided into two-step self-etching (Clearfil SE Bond) or all-in-one self-etching (Xeno IV) adhesive systems. Resin composite microtubes were bonded according to dentin location—center, pulp horn, and peripheral positions—and an MSBS test was carried out. Failure mode was determined using light microscopy and scanning electron microscopy. There were no significant differences between the treatment types/groups. MSBSs were significantly higher for two-step self-etching adhesive compared with all-in-one self-etching adhesive (p=0.028). For the all-in-one adhesive, MSBSs at the center and pulp horn positions were significantly lower than the peripheral positions (p<0.001). All-in-one groups had significantly more adhesive failures than two-step adhesive groups (p=0.015). The odds of adhesive failure were higher at the pulp horn position than the peripheral position (p=0.004). Sodium perborate bleaching of dentin had no effect on MSBS or mode of failure for either two-step or all-in-one self-etching adhesives; therefore, the effect of sodium ascorbate was negligible. The two-step adhesive groups demonstrated the highest MSBS, and the all-in-one groups, when bonded to center and pulp horn dentin, exhibited the lowest MSBS.
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100
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Ahn S, Cho K, Jeong J, Yoon M, Song J, Nam T, Ban H, Oh I, Kim K, Kim Y. Randomized, Multicenter Phase 3 Study of Accelerated Fraction With Concomitant Boost to the Gross Tumor Volume Compared With Conventional Fraction in Concurrent Chemoradiation in Patients With Unresectable Stage III Non-Small Cell Lung Cancer: KROG 0903. Int J Radiat Oncol Biol Phys 2013. [DOI: 10.1016/j.ijrobp.2013.06.196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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