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Journal of Physical Chemistry Letters

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https://www.readbyqxmd.com/read/29140702/influence-of-the-carotenoid-composition-on-the-conformational-dynamics-of-photosynthetic-light-harvesting-complexes
#1
Marijonas Tutkus, Jevgenij Chmeliov, Danielis Rutkauskas, Alexander V Ruban, Leonas Valkunas
Non-photochemical quenching (NPQ) is the major self-regulatory mechanism of green plant, performed on a molecular level to protect them from an over-excitation during the direct sunlight. It is believed that NPQ becomes available due to conformational dynamics of the light-harvesting photosynthetic complexes and involves a direct participation of carotenoids. In this work, we perform a single-molecule microscopy on major light-harvesting complexes (LHCII) from different Arabidopsis thaliana mutants exhibiting various carotenoid composition...
November 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29139292/enhanced-electrical-properties-and-air-stability-of-amorphous-organic-thin-films-by-engineering-film-density
#2
Yu Esaki, Takeshi Komino, Toshinori Matsushima, Chihaya Adachi
The influences of film density and molecular orientation on the carrier conduction and air stability of vacuum-deposited amorphous organic films of N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (α-NPD) were investigated. The substrate temperature (Tsub) during vacuum deposition had different effects on the film density and molecular orientation of α-NPD. Film density was a concave function of Tsub; maximum density was attained at Tsub = 270-300 K (0.75-0.83 of the glass transition temperature)...
November 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29136471/below-room-temperature-c-h-bond-breaking-on-an-inexpensive-metal-oxide-methanol-to-formaldehyde-on-ceo2-111
#3
Jonathan E Sutton, Thomas Danielson, Ariana Beste, Aditya Savara
Upgrading of primary alcohols by C-H bond breaking currently requires temperatures of >200 °C. In this work, new understanding from simulation of a temperature-programmed reaction study with methanol over a CeO2(111) surface shows C-H bond breaking and the subsequent desorption of formaldehyde, even below room temperature. This is of particular interest because CeO2 is a naturally abundant and inexpensive metal oxide. We combine density functional theory and kinetic Monte Carlo methods to show that the low-temperature C-H bond breaking occurs via disproportionation of adjacent methoxy species...
November 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29131962/intercalation-and-deintercalation-of-lithium-at-the-ionic-liquid-graphite-0001-interface
#4
Florian Buchner, Jihyun Kim, Christiane Adler, Maral Bozorgchenani, Joachim Bansmann, R Jürgen Behm
The intercalation and deintercalation of lithium (Li) into / out of graphite(0001), which is a highly important process in Li-ion batteries, was investigated under ultrahigh vacuum conditions as a function of temperature, employing X-ray and ultraviolet photoelectron spectroscopy. Both the up-shifts of the core-level binding energy and the lowering of the work function ΔΦ reveal that heating of a monolayer of the battery-relevant ionic liquid (IL) 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP](+)[TFSI](-)) adsorbed on lithiated graphite at 80 K to >230 K facilitates an accumulation of partially charged Li(δ+) atoms at the IL-graphite(0001) interface...
November 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29130309/impact-of-chemical-doping-on-optical-responses-in-bismuth-doped-ch3nh3pbbr3-single-crystals-carrier-lifetime-and-photon-recycling
#5
Yasuhiro Yamada, Mizuki Hoyano, Ryo Akashi, Kenichi Oto, Yoshihiko Kanemitsu
We studied the optical responses of organic-inorganic halide perovskite CH3NH3PbBr3 single crystals doped with heterovalent Bi(3+) ions (electron densities up to 2.3 × 10(12) cm(-3)). The Bi doping causes no significant changes in the band gap energy but leads to an enhanced Urbach tail and photoluminescence blue shift. On the basis of the time-resolved photoluminescence measurements, we attribute the PL response to a shorter carrier lifetime induced by Bi doping, which results in a reduced photon recycling effect (i...
November 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29116791/soluble-oligomeric-nucleants-simulations-of-chain-length-binding-strength-and-volume-fraction-effects
#6
Geoffrey G Poon, Tobias Lemke, Christine Peter, Valeria Molinero, Baron Peters
Recent theories and simulations suggest that molecular additives can bind to the surfaces of nuclei, lower the surface energy, and accelerate nucleation. Experiments have shown that oligomeric and polymeric additives can also modify nucleation rates of proteins, ice, and minerals; however, general design principles for oligomeric or polymeric promoters do not yet exist. Here we investigate oligomeric additives for which each segment of the oligomer can bind to surfaces of nuclei. We use semigrand canonical Monte Carlo simulations in a Potts lattice gas model to study the effects of oligomer chain length, volume fraction, and binding strength...
November 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29131650/revealing-the-solvation-structure-and-dynamics-of-carbonate-electrolytes-in-lithium-ion-batteries-by-two-dimensional-infrared-spectrum-modeling
#7
Chungwen Liang, Kyungwon Kwak, Minhaeng Cho
Carbonate electrolytes in lithium-ion batteries play a crucial role in conducting lithium ions between two electrodes. Mixed solvent electrolytes consisting of linear and cyclic carbonates are commonly used in commercial lithium-ion batteries. To understand how the linear and cyclic carbonates introduce different solvation structures and dynamics, we performed molecular dynamics simulations of two representative electrolyte systems containing either linear or cyclic carbonate solvents. We then modeled their two-dimensional infrared (2DIR) spectra of the carbonyl stretching mode of these carbonate molecules...
November 14, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29129083/giant-valley-splitting-and-valley-polarized-plasmonics-in-group-v-transition-metal-dichalcogenide-monolayers
#8
Jian Zhou, Puru Jena
Two-dimensional group VI transition-metal dichalcogenides (TMDs) provide a promising platform to encode and manipulate quantum information in the valleytronics. However, the two valleys are energetically degenerate, protected by time-reversal symmetry (TRS). To lift this degeneracy, one needs to break the TRS by either applying an external magnetic field or using a magnetic rare-earth oxide substrate. Here, we predict a different strategy to achieve this goal. We propose that the ferromagnetic group V TMD monolayer, in which the TRS is intrinsically broken, can produce a larger valley and spin splitting...
November 14, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29129078/disparity-in-photoexcitation-dynamics-between-vertical-and-lateral-mos2-wse2-heterojunctions-time-domain-simulation-emphasizes-the-importance-of-donor-acceptor-interaction-and-band-alignment
#9
Yating Yang, Wei-Hai Fang, Run Long
Two-dimensional transition metal dichalcogenides (TMDs) heterojunctions are appealing candidates for optoelectronics and photovoltaics. Using time-domain density functional theory combined with nonadiabatic (NA) molecular dynamics, we show that photoexcitation dynamics exhibit a significant difference in the vertical and lateral MoS2/WSe2 heterojunctions arising from the disparity in the donor-acceptor interaction and fundamental band alignment. The obtained electron transfer time scale in the vertical heterojunction shows excellent agreement with experiment...
November 14, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29116810/structural-evolution-of-lixniymnzco1-y-zo2-cathode-materials-during-high-rate-charge-and-discharge
#10
Sooyeon Hwang, Eunmi Jo, Kyung Yoon Chung, Kyo Seon Hwang, Seung Min Kim, Wonyoung Chang
Ni-rich lithium transition metal oxides have received significant attention due to their high capacities and rate capabilities determined via theoretical calculations. Although the structural properties of these materials are strongly correlated with the electrochemical performance, their structural stability during the high-rate electrochemical reactions has not been fully evaluated yet. In this work, transmission electron microscopy is used to investigate the crystallographic and electronic structural modifications of Ni-based cathode materials at a high charge/discharge rate of 10 C...
November 14, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29131951/nanoscopic-approach-to-quantification-of-equilibrium-and-rate-constants-of-complex-formation-at-single-molecule-level
#11
Xuzhu Zhang, Evangelos Sisamakis, Krzysztof Sozanski, Robert Holyst
Equilibrium and rate constants are key descriptors of complex-formation processes in a variety of chemical and biological reactions. However, these parameters are difficult to quantify, especially in the locally confined, heterogeneous, and dynamically changing living matter. Herein, we address this challenge by combining stimulated emission depletion (STED) nanoscopy with fluorescence correlation spectroscopy (FCS). STED reduces the length-scale of observation to tens of nanometres (2D)/attoliters (3D) and the time-scale-to microseconds, with direct, gradual control...
November 13, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29125304/homogeneous-nucleation-of-ice-in-transiently-heated-supercooled-liquid-water-films
#12
Yuntao Xu, Nikolay G Petrik, R Scott Smith, Bruce D Kay, Greg A Kimmel
We have investigated the nucleation and growth of crystalline ice in 0.24 μm thick, supercooled water films adsorbed on Pt(111). The films were transiently heated with ∼10 ns infrared laser pulses, which produced typical heating and cooling rates of ∼10(9)-10(10) K/s. The crystallization of these water films was monitored with infrared spectroscopy. The experimental conditions were chosen to suppress ice nucleation at both the water/metal and water/vacuum interfaces. Furthermore, internal pressure increases due to curvature effects are precluded in these flat films...
November 13, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29125300/ultrafast-synthesis-and-coating-of-high-quality-%C3%AE-nayf4-yb-3-ln-3-short-nanorods
#13
Fabrizio Guzzetta, Anna Roig, Beatriz Julián-López
An ultrafast route to prepare up-converting single β-phase NaYF4:Yb(3+),Ln(3+) (Ln: Er, Tm, or Tb) short nanorods (UCNRs) of high quality was developed. This new procedure affords reactive-surface nanorods that are easily coated by direct injection of suitable capping ligands. Thus highly crystalline nanorods with excellent UC fluorescence and good solvent-selective dispersion are obtained, which represents a significant advance in the field and enlarges their use for biomedical and other technological applications...
November 13, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29112436/capturing-the-elusive-water-trimer-from-the-stepwise-growth-of-water-on-the-surface-of-the-polycyclic-aromatic-hydrocarbon-acenaphthene
#14
Amanda L Steber, Cristóbal Pérez, Berhane Temelso, George C Shields, Anouk M Rijs, Brooks H Pate, Zbigniew Kisiel, Melanie Schnell
Polycyclic aromatic hydrocarbons (PAHs) are key players in reaction chemistry. While it is postulated that they serve as a basis for ice grains, there has been no direct detection of PAHs in astronomical environments. We aim to investigate the hydration of PAHs to set a foundation for the future exploration of potential ice formation pathways. We report results from chirped pulse Fourier transform microwave spectroscopy and quantum-chemical calculations for the PAH acenaphthene and acenaphthene complexed with up to four water molecules...
November 13, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29129082/first-principles-study-of-electron-injection-and-defects-at-the-tio2-ch3nh3pbi3-interface-of-perovskite-solar-cells
#15
Jun Haruyama, Keitaro Sodeyama, Ikutaro Hamada, Liyuan Han, Yoshitaka Tateyama
We investigated electron injection rates and vacancy defect properties by performing first-principles calculations on the interface of an anatase-TiO2(001) and a tetragonal CH3NH3PbI3(110) (MAPbI3(110)). We found that the coupling matrix element between the lowest unoccupied molecular orbital of MAPbI3 and the TiO2 conduction band (CB) minimum is negligibly small, the indication being that electron-injection times for low-energy excited states quite long (> several tens of picoseconds). We also found that higher-lying CB states coupled more strongly; injection was expected to take place on a femtosecond time scale...
November 16, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29129074/from-type-ii-triply-degenerate-nodal-points-and-three-band-nodal-rings-to-type-ii-dirac-points-in-centrosymmetric-zirconium-oxide
#16
Ting-Ting Zhang, Zhi-Ming Yu, Wei Guo, Dongxia Shi, Guangyu Zhang, Yugui Yao
Using first-principles calculations, we report that ZrO is a topological material with the coexistence of three pairs of type-II triply degenerate nodal points (TNPs) and three nodal rings (NRs), when spin-orbit coupling (SOC) is ignored. Noticeably, the TNPs reside around Fermi energy with large linear energy range along tilt direction (> 1 eV) and the NRs are formed by three strongly entangled bands. Under symmetry-preserving strain, each NR would evolve into four droplet-shaped NRs before fading away, producing distinct evolution compared with that in usual two-band NR...
November 12, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29125301/photon-antibunching-reveals-static-and-dynamic-quenching-interaction-of-tryptophan-with-atto-655
#17
Arjun Sharma, Joerg Enderlein, Manoj Kumbhakar
Fluorescence correlation spectroscopy (FCS) of photoinduced electron transfer (PET) between the dye Atto-655 and the amino acid tryptophan has been extensively used for studying fast conformational dynamics of small disordered peptides and proteins. However, a precise understanding of the quenching mechanism and its exact rates that would explain ensemble as well as single molecule spectroscopy results is still lacking. In this contribution, a general unified model for intermolecular PET between Atto-655 and tryptophan is developed, which involves ground state complex formation, quenching sphere of action, and dynamic quenching at the single molecule level...
November 10, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29125299/charge-driven-fluorescence-blinking-in-carbon-nanodots
#18
Syamantak Khan, Weixing Li, Narain Karedla, Jan Thiart, Ingo Gregor, Anna M Chizhik, Joerg Enderlein, Chayan Kanti Nandi, Alexey I Chizhik
This study focuses on the mechanism of fluorescence blinking of single carbon nanodots, which is one of their key but less understood properties. The results of our single particle fluorescence study show that the mechanism of carbon nanodots blinking has remarkable similarities with that of semiconductor quantum dots. In particular, the temporal behavior of carbon nanodot blinking follows a power law both at room and at cryogenic temperatures. Our experimental data suggests that static quenching via Dexter type electron transfer between surface groups of a nanoparticle plays a major role in the transition of carbon nanodots to off- or grey states, whereas the transition back to on-states is governed by an electron tunneling from the particle's core...
November 10, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29121464/the-experimental-measurement-of-local-and-bulk-oxygen-transport-resistances-in-the-catalyst-layer-of-proton-exchange-membrane-fuel-cells
#19
Chao Wang, Xiaojing Cheng, Jiabin Lu, Shuiyun Shen, Xiaohui Yan, Jiewei Yin, Guanghua Wei, Junliang Zhang
Remarkable progress has been made in reducing the cathodic Pt loading of PEMFCs, however, a huge performance loss appears at high current densities, indicating the existence of a large oxygen transport resistance associated with the ultralow Pt-loading catalyst layer. To reduce the Pt loading without sacrificing cell performance, it is essential to illuminate the oxygen transport mechanism in the catalyst layer. Towards this goal, an experimental approach to measure the oxygen transport resistance in catalyst layers is proposed and realized for the first time in this study...
November 9, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29120643/identification-of-single-adsorbed-cations-on-mica-liquid-interfaces-by-3d-force-microscopy
#20
Daniel Martin-Jimenez, Ricardo Garcia
Force microscope provides atomically resolved images of surfaces immersed in a liquid. The presence of different chemical species in the interface (cations, anions, water, neutral atoms) complicates the adscription of the observed features to a given species. We develop a 3D atomic force microscopy method to identify the cations adsorbed on a mica surface from a potassium chloride solution. The method is based on measuring the peak value of the attractive force within the Stern layer. The maximum of the attractive force shows site-specific variations...
November 9, 2017: Journal of Physical Chemistry Letters
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