Imaging Photodissociation Dynamics of MgO at 193 nm

In this work, we used time-sliced ion velocity imaging to study the photodissociation dynamics of MgO at \mbox{193 nm}. Three dissociation pathways are found through the speed and angular distributions of magnesium. One pathway is the one-photon excitation of MgO(X\begin{document}$^1\Sigma^+$\end{document}) to MgO(G\begin{document}$^1\Pi$\end{document}) followed by spin-orbit coupling between the G\begin{document}$^1\Pi$\end{document}, 3\begin{document}$^3\Pi$\end{document} and 1\begin{document}$^5\Pi$\end{document} states, and finally dissociated to the Mg(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{u}$\end{document})+O(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{g}$\end{document}) along the 1\begin{document}$^5\Pi$\end{document} surface. The other two pathways are one-photon absorption of MgO(A\begin{document}$^1\Pi$\end{document}) state to MgO(G\begin{document}$^1\Pi$\end{document}) and MgO(4\begin{document}$^1\Pi$\end{document}) state to dissociate into Mg(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{u}$\end{document})+O(\begin{document}$^3$\end{document}P\begin{document}$_\textrm{g}$\end{document}) and Mg(\begin{document}$^1$\end{document}S\begin{document}$_\textrm{g}$\end{document})+O(\begin{document}$^1$\end{document}S\begin{document}$_\textrm{g}$\end{document}), respectively. The anisotropy parameters of the dissociation pathways are related to the lifetime of the vibrational energy levels and the coupling of rotational and vibronic spin-orbit states. The total kinetic energy analysis gives \begin{document}$D_0$\end{document}(Mg\begin{document}$-$\end{document}O)=21645\begin{document}$\pm$\end{document}50 cm\begin{document}$^{-1}$\end{document}.     

H-Atom Transfer Reaction of Photoinduced Excited Triplet Duroquinone with Tryptophan and Tyrosine in Acetonitrile-Water and Ethylene Glycol-Water Homogeneous Solutions

Laser flash photolysis was used to investigate the photoinduced reactions of excited triplet bioquinone molecule duroquinone (DQ) with tryptophan (Trp) and tyrosine (Tyr) in acetonitrile-water (MeCN-H\begin{document}$_2$\end{document}O) and ethylene glycol-water (EG-H\begin{document}$_2$\end{document}O) solutions. The reaction mechanisms were analyzed and the reaction rate constants were measured based on Stern-Volmer equation. The H-atom transfer reaction from Trp (Tyr) to \begin{document}$^3$\end{document}DQ\begin{document}$^*$\end{document} is dominant after the formation of \begin{document}$^3$\end{document}DQ\begin{document}$^*$\end{document} during the laser photolysis. For DQ and Trp in MeCN-H\begin{document}$_2$\end{document}O and EG-H\begin{document}$_2$\end{document}O solutions, \begin{document}$^3$\end{document}DQ\begin{document}$^*$\end{document} captures H-atom from Trp to generate duroquinone neutral radical DQH\begin{document}$^\bullet$\end{document}, carbon-centered tryptophan neutral radical Trp\begin{document}$^\bullet$\end{document}/NH and nitrogen-centered tryptophan neutral radical Trp/N\begin{document}$^\bullet$\end{document}. For DQ and Tyr in MeCN-H\begin{document}$_2$\end{document}O and EG-H\begin{document}$_2$\end{document}O solutions, \begin{document}$^3$\end{document}DQ\begin{document}$^*$\end{document} captures H-atom from Tyr to generate duroquinone neutral radical DQH\begin{document}$^\bullet$\end{document} and tyrosine neutral radical Tyr/O\begin{document}$^\bullet$\end{document}. The H-atom transfer reaction rate constant of \begin{document}$^3$\end{document}DQ\begin{document}$^*$\end{document} with Trp (Tyr) is on the level of 10\begin{document}$^9$\end{document} L\begin{document}$\cdot$\end{document}mol\begin{document}$^{-1}$\end{document}\begin{document}$\cdot$\end{document}s\begin{document}$^{-1}$\end{document}, nearly controlled by diffusion. The reaction rate constant of \begin{document}$^3$\end{document}DQ\begin{document}$^*$\end{document} with Trp (Tyr) in MeCN/H\begin{document}$_2$\end{document}O solution is larger than that in EG/H\begin{document}$_2$\end{document}O solution, which agrees with Stokes-Einstein relationship qualitatively.     

Structures,Energetics, and Infrared Spectra of the Cationic Monomethylamine-Water Clusters

The structures, energetics, and infrared (IR) spectra of the cationic monomethylamine-water clusters, [(CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document})(H\begin{document}$_2$\end{document}O)\begin{document}$_n$\end{document}]\begin{document}$^+$\end{document} (\begin{document}$n$\end{document}=1\begin{document}$-$\end{document}5), have been studied using quantum chemical calculations at the MP2/6-311+G(2d,p) level. The results reveal that the formation of proton-transferred CH\begin{document}$_2$\end{document}NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document} ion core structure is preferred via the intramolecular proton transfer from the methyl group to the nitrogen atom and the water molecules act as the acceptor for the O\begin{document}$\cdots$\end{document}HN hydrogen bonds with the positively charged NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document} moiety of CH\begin{document}$_2$\end{document}NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document}, whose motif is retained in the larger clusters. The CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document}\begin{document}$^+$\end{document} ion core structure is predicted to be less energetically favorable. Vibrational frequencies of CH stretches, hydrogen-bonded and free NH stretches, and hydrogen-bonded OH stretches in the calculated IR spectra of the CH\begin{document}$_2$\end{document}NH\begin{document}$_3$\end{document}\begin{document}$^+$\end{document} and CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document}\begin{document}$^+$\end{document} type structures are different from each other, which would afford the sensitive probes for fundamental understanding of hydrogen bonding networks generated from the radiation-induced chemical processes in the [(CH\begin{document}$_3$\end{document}NH\begin{document}$_2$\end{document})(H\begin{document}$_2$\end{document}O)\begin{document}$_n$\end{document}]\begin{document}$^+$\end{document} complexes.     

Experimental and Theoretical Study on Dissociative Photoionization of Cyclopentanone

The dissociative photoionization of cyclopentanone was investigated by means of a reflectron time-of-flight mass spectrometer (RTOF-MS) with tunable vacuum ultraviolet synchrotron radiation in the photon energy range of 9.0-15.5 eV. The photoionization efficiency (PIE) curves for molecular ion and fragment ions were measured. The ionization energy of cyclopentanone was determined to be 9.23\begin{document}$\pm$\end{document}0.03 eV. Fragment ions from the dissociative photoionization of cyclopentanone were identified as C\begin{document}$_5$\end{document}H\begin{document}$_7$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_4$\end{document}H\begin{document}$_5$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_4$\end{document}H\begin{document}$_8^+$\end{document}/C\begin{document}$_3$\end{document}H\begin{document}$_4$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_3$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_4$\end{document}H\begin{document}$_6^+$\end{document}, C\begin{document}$_2$\end{document}H\begin{document}$_4$\end{document}O\begin{document}$^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_6^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_5^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_4^+$\end{document}, C\begin{document}$_3$\end{document}H\begin{document}$_3^+$\end{document}, C\begin{document}$_2$\end{document}H\begin{document}$_5^+$\end{document} and C\begin{document}$_2$\end{document}H\begin{document}$_4^+$\end{document}. With the aid of the ab initio calculations at the \begin{document}$\omega$\end{document}B97X-D/6-31+G(d, p) level of theory, the dissociative mechanisms of C\begin{document}$_5$\end{document}H\begin{document}$_8$\end{document}O\begin{document}$^+$\end{document} are proposed. Ring opening and hydrogen migrations are the predominant processes in most of the fragmentation pathways of cyclopentanone.     

Three-Dimensional Diabatic Potential Energy Surfaces of Thiophenol with Neural Networks

Three-dimensional (3D) diabatic potential energy surfaces (PESs) of thiophenol involving the S\begin{document}$_0$\end{document}, and coupled \begin{document}$^1$\end{document}\begin{document}$\pi\pi^*$\end{document} and \begin{document}$^1$\end{document}\begin{document}$\pi\sigma^*$\end{document} states were constructed by a neural network approach. Specifically, the diabatization of the PESs for the \begin{document}$^1$\end{document}\begin{document}$\pi\pi^*$\end{document} and \begin{document}$^1\pi\sigma^*$\end{document} states was achieved by the fitting approach with neural networks, which was merely based on adiabatic energies but with the correct symmetry constraint on the off-diagonal term in the diabatic potential energy matrix. The root mean square errors (RMSEs) of the neural network fitting for all three states were found to be quite small (\begin{document}$<$\end{document}4 meV), which suggests the high accuracy of the neural network method. The computed low-lying energy levels of the S\begin{document}$_0$\end{document} state and lifetime of the 0\begin{document}$^0$\end{document} state of S\begin{document}$_1$\end{document} on the neural network PESs are found to be in good agreement with those from the earlier diabatic PESs, which validates the accuracy and reliability of the PESs fitted by the neural network approach.     

Sum Frequency Spectroscopy Studies on Cell Membrane Fusion Induced by Divalent Cations

Cell membrane fusion is a fundamental biological process involved in a number of cellular living functions. Regarding this, divalent cations can induce fusion of the lipid bilayers through binding and bridging of divalent cations to the charged lipids, thus leading to the cell membrane fusion. However, the elaborate mechanism of cell membrane fusion induced by divalent cations is still needed to be elucidated. Here, surface/interface sensitive sum frequency generation vibrational spectroscopy (SFG-VS) and dynamic light scattering (DLS) were applied in this research to study the responses of phospholipid monolayer to the exposure of divalent metal ions i.e. Ca\begin{document}$ ^{2+} $\end{document} and Mg\begin{document}$ ^{2+} $\end{document}. According to the particle size distribution results measured by DLS experiments, it was found that Ca\begin{document}$ ^{2+} $\end{document} could induce inter-vesicular fusion while Mg\begin{document}$ ^{2+} $\end{document} could not. An octadecyltrichlorosilane self-assembled monolayer (OTS SAM)-lipid monolayer system was designed to model the cell membrane for the SFG-VS experiment. Ca\begin{document}$ ^{2+} $\end{document} could interact with the lipid PO\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} head groups more strongly, resulting in cell membrane fusion more easily, in comparison with Mg\begin{document}$ ^{2+} $\end{document}. No specific interaction between the two metal cations and the C=O groups was observed. However, the C=O orientations changed more after Ca\begin{document}$ ^{2+} $\end{document}-PO\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} binding than Mg\begin{document}$ ^{2+} $\end{document} mediation on lipid monolayer. Meanwhile, Ca\begin{document}$ ^{2+} $\end{document} could induce dehydration of the lipids (which should be related to the strong Ca\begin{document}$ ^{2+} $\end{document}-PO\begin{document}$ _2 $\end{document}\begin{document}$ ^- $\end{document} interaction), leading to the reduced hindrance for cell membrane fusion.     

Influence of Molecular Stacking Pattern on Excited State Dynamics of Copper Phthalocyanine Films

Photophysical processes occurring within organic semiconductors is important for designing and fabricating organic solar cells. Copper phthalocyanine (CuPc) is a typical electron acceptor. In this work, the triplet exciton lifetime is prolonged by altering the molecular stacking pattern of the CuPc film. For CuPc thin films, the excited state decays are mainly determined by the triplet-triplet annihilation process. The ultrafast transient absorption measurements indicate that the primary annihilation mechanism is one-dimensional exciton diffusion collision destruction. The decay kinetics show a clearly time-dependent annihilation rate constant with \begin{document}$\gamma$\end{document}\begin{document}$\propto$\end{document}\begin{document}$t^{-1/2}$\end{document}. Annihilation rate constants are determined to be \begin{document}$\gamma_0$\end{document}=(2.87\begin{document}$\pm$\end{document}0.02)\begin{document}$\times$\end{document}10\begin{document}$^{-20}$\end{document} cm\begin{document}$^3$\end{document}\begin{document}$\cdot$\end{document}s\begin{document}$^{-1/2}$\end{document} and (1.42\begin{document}$\pm$\end{document}0.02)\begin{document}$\times$\end{document}10\begin{document}$^{-20}$\end{document} cm\begin{document}$^3$\end{document}\begin{document}$\cdot$\end{document}s\begin{document}$^{-1/2}$\end{document} for upright and lying-down configurations, respectively. Compared to the CuPc thin film with an upright configuration, the thin film with a lying-down configuration shows longer exciton lifetime and higher absorbance, which are beneficial to organic solar cells. The results in this work have important implications on the design and mechanistic understanding of organic optoelectronic devices.     

Excited State Trap in Erbium Doped Borate Glass

Erbium doped borate glass is widely used in luminescent materials, the luminescence dynamics of erbium doped borate glass is of great significance for optimizing and improving the luminous efficiency. The 2% molar ratio erbium doped borate glass was synthesized by the traditional melt quenching method, and annealed at 260 \begin{document}$^{\circ}$\end{document}C below the borate glass transition temperature. The thermal performance parameters of borate glass undoped and doped with Er\begin{document}$^{3+}$\end{document} were measured by differential scanning calorimetry with 10 \begin{document}$^{\circ}$\end{document}C/min. The transient emission spectrum and decay kinetics curves were measured for the luminescence mechanism of erbium doped borate. Er\begin{document}$^{3+}$\end{document} ions have different lifetime when emitted at 556 nm with different excitation wavelengths, the excited state trap may exist in erbium doped borate glass.     

Doping Copper Ions in a Metal-Organic Framework (UiO-66-NH2):Location Effect Examined by Ultrafast Spectroscopy

We constructed two types of copper-doped metal-organic framework (MOF), i.e., Cu@UiO-66-NH\begin{document}$ _2 $\end{document} and Cu-UiO-66-NH\begin{document}$ _2 $\end{document}. In the former, Cu\begin{document}$ ^{2+} $\end{document} ions are impregnated in the pore space of the amine-functionalized, Zr-based UiO-66-NH\begin{document}$ _2 $\end{document}; while in the latter, Cu\begin{document}$ ^{2+} $\end{document} ions are incorporated to form a bimetal-center MOF, with Zr\begin{document}$ ^{4+} $\end{document} being partially replaced by Cu\begin{document}$ ^{2+} $\end{document} in the Zr\begin{document}$ - $\end{document}O oxo-clusters. Ultrafast spectroscopy revealed that the photoinduced relaxation kinetics associated with the ligand-to-cluster charge-transfer state is promoted for both Cu-doped MOFs relative to undoped one, but in a sequence of Cu-UiO-66-NH\begin{document}$ _2 $\end{document}\begin{document}$ > $\end{document}Cu@UiO-66-NH\begin{document}$ _2 $\end{document}\begin{document}$ > $\end{document}UiO-66-NH\begin{document}$ _2 $\end{document}. Such a sequence turned to be in line with the trend observed in the visible-light photocatalytic hydrogen evolution activity tests on the three MOFs. These findings highlighted the subtle effect of copper-doping location in this Zr-based MOF system, further suggesting that rational engineering of the specific metal-doping location in alike MOF systems to promote the photoinduced charge separation and hence suppress the detrimental charge recombination therein is beneficial for achieving improved performances in MOF-based photocatalysis.     

"Dry" NiCo\begin{document}$_\textbf{2}$\end{document}O\begin{document}$_\textbf{4}$\end{document} Nanorods for Electrochemical Non-enzymatic Glucose Sensing

A rod-like NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document} modified glassy carbon electrode was fabricated and used for non-enzymatic glucose sensing. The NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document} was prepared by a facile hydrothermal reaction and subsequently treated in a commercial microwave oven to eliminate the residual water introduced during the hydrothermal procedure. Structural analysis showed that there was no significant structural alteration before and after microwave treatment. The elimination of water residuals was confirmed by the stoichiometric ratio change by using element analysis. The microwave treated NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document} (M-NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document}) showed excellent performance as a glucose sensor (sensitivity 431.29 \begin{document}$\mu $\end{document}A\begin{document}$\cdot$\end{document}mmol/L\begin{document}$^{-1}$\end{document}\begin{document}$\cdot$\end{document}cm\begin{document}$^{-2}$\end{document}). The sensing performance decreases dramatically by soaking the M-NiCo\begin{document}$_2$\end{document}O\begin{document}$_4$\end{document} in water. This result indicates that the introduction of residual water during hydrothermal process strongly affects the electrochemical performance and microwave pre-treatment is crucial for better sensory performance.     

Atomistic Mechanisms for Catalytic Transformations of NO to NH3, N2O,and N2 by Pd

The industrial pollutant NO is a potential threat to the environment and to human health. Thus, selective catalytic reduction of NO into harmless N\begin{document}$_2$\end{document}, NH\begin{document}$_3$\end{document}, and/or N\begin{document}$_2$\end{document}O gas is of great interest. Among many catalysts, metal Pd has been demonstrated to be most efficient for selectivity of reducing NO to N\begin{document}$_2$\end{document}. However, the reduction mechanism of NO on Pd, especially the route of N\begin{document}$-$\end{document}N bond formation, remains unclear, impeding the development of new, improved catalysts. We report here the elementary reaction steps in the reaction pathway of reducing NO to NH\begin{document}$_3$\end{document}, N\begin{document}$_2$\end{document}O, and N\begin{document}$_2$\end{document}, based on density functional theory (DFT)-based quantum mechanics calculations. We show that the formation of N\begin{document}$_2$\end{document}O proceeds through an Eley-Rideal (E-R) reaction pathway that couples one adsorbed NO\begin{document}$^*$\end{document} with one non-adsorbed NO from the solvent or gas phase. This reaction requires high NO\begin{document}$^*$\end{document} surface coverage, leading first to the formation of the trans-(NO)\begin{document}$_2$\end{document}\begin{document}$^*$\end{document} intermediate with a low N\begin{document}$-$\end{document}N coupling barrier (0.58 eV). Notably, trans-(NO)\begin{document}$_2$\end{document}\begin{document}$^*$\end{document} will continue to react with NO in the solvent to form N\begin{document}$_2$\end{document}O, that has not been reported. With the consumption of NO and the formation of N\begin{document}$_2$\end{document}O\begin{document}$^*$\end{document} in the solvent, the Langmuir-Hinshelwood (L-H) mechanism will dominate at this time, and N\begin{document}$_2$\end{document}O\begin{document}$^*$\end{document} will be reduced by hydrogenation at a low chemical barrier (0.42 eV) to form N\begin{document}$_2$\end{document}. In contrast, NH\begin{document}$_3$\end{document} is completely formed by the L-H reaction, which has a higher chemical barrier (0.87 eV). Our predicted E-R reaction has not previously been reported, but it explains some existing experimental observations. In addition, we examine how catalyst activity might be improved by doping a single metal atom (M) at the NO\begin{document}$^*$\end{document} adsorption site to form M/Pd and show its influence on the barrier for forming the N\begin{document}$-$\end{document}N bond to provide control over the product distribution.     

Ag-Cu Nanoparticles Supported on N-Doped TiO\begin{document}$_2$\end{document} Nanowire Arrays for Efficient Photocatalytic CO\begin{document}$_2$\end{document} Reduction

Photocatalytic reduction of CO\begin{document}$_2$\end{document} into various types of fuels has attracted great interest, and serves as a potential solution to addressing current global warming and energy challenges. In this work, Ag-Cu nanoparticles are densely supported on N-doped TiO\begin{document}$_2$\end{document} nanowire through a straightforward nanofabrication approach. The range of light absorption by N-doped TiO\begin{document}$_2$\end{document} can be tuned to match the plasmonic band of Ag nanoparticles, which allows synergizing a resonant energy transfer process with the Schottky junction. Meanwhile, Cu nanoparticles can provide active sites for the reduction of CO\begin{document}$_2$\end{document} molecules. Remarkably, the performance of photocatalytic CO\begin{document}$_2$\end{document} reduction is improved to produce CH\begin{document}$_4$\end{document} at a rate of 720 \begin{document}$\mu$\end{document}mol\begin{document}$\cdot$\end{document}g\begin{document}$^{-1}$\end{document}\begin{document}$\cdot$\end{document}h\begin{document}$^{-1}$\end{document} under full-spectrum irradiation.     

Photodissociation Dynamics of CS2 Near 204 nm: The S(3PJ)+CS(X1Σ+)Channels

We study the photodissociation dynamics of CS\begin{document}$_2$\end{document} in the ultraviolet region using the time-sliced velocity map ion imaging technique. The S(\begin{document}$^3$\end{document}P\begin{document}$_J$\end{document})+CS(\begin{document}$X^1\Sigma^+$\end{document}) product channels were observed and identified at four wavelengths of 201.36, 203.10, 204.85 and 206.61 nm. In the measured images of S(\begin{document}$^3$\end{document}P\begin{document}$_{J=2, 1, 0}$\end{document}), the vibrational states of the CS(\begin{document}$X^1\Sigma^+$\end{document}) co-products were partially resolved and the vibrational state distributions were determined. Moreover, the product total kinetic energy releases and the anisotropic parameters were derived. The relatively small anisotropic parameter values indicate that the S(\begin{document}$^3$\end{document}P\begin{document}$_{J=2, 1, 0}$\end{document})+CS(\begin{document}$X^1\Sigma^+$\end{document}) channels are very likely formed via the indirect predissociation process of CS\begin{document}$_2$\end{document}. The study of the S(\begin{document}$^3$\end{document}P\begin{document}$_{J=2, 1, 0}$\end{document})+CS(\begin{document}$X^1\Sigma^+$\end{document}) channels, which come from the spin-orbit coupling dissociation process of CS\begin{document}$_2$\end{document}, shows that nonadiabatic process plays a role in the ultraviolet photodissociation of CS\begin{document}$_2$\end{document}.     

Gamma Ray Radiation Effect on \begin{document}$\rm{{Bi}}_{2}$\end{document}W\begin{document}$\rm{{O}}_{6}$\end{document} Photocatalyst

The development of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document}-based materials has become one of research hotspots due to the increasing demands on high-efficient photocatalyst responding to visible light. In this work, the effect of high energy radiation (\begin{document}$\gamma$\end{document}-ray) on the structure and the photocatalytic activity of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals was first studied. No morphological change of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals was observed by SEM under \begin{document}$\gamma$\end{document}-ray radiation. However, the XRD spectra of the irradiated \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals showed the characteristic 2\begin{document}$\theta$\end{document} of (113) plane shifts slightly from 28.37\begin{document}$^{\rm{o}}$\end{document} to 28.45\begin{document}$^{\rm{o}}$\end{document} with the increase of the absorbed dose, confirming the change in the crystal structure of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document}. The XPS results proved the crystal structure change was originated from the generation of oxygen vacancy defects under high-dose radiation. The photocatalytic activity of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} on the decomposition of methylene blue (MB) in water under visible light increases gradually with the increase of absorbed dose. Moreover, the improved photocatalytic performance of the irradiated \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} nanocrystals remained after three cycles of photocatalysis, indicating a good stability of the created oxygen vacancy defects. This work gives a new simple way to improve photocatalytic performance of \begin{document}$\rm{Bi}_2$\end{document}W\begin{document}$\rm{O}_6$\end{document} through creating oxygen vacancy defects in the crystal structure by \begin{document}$\gamma$\end{document}-ray radiation.     

Improving Interfacial Electrochemistry of LiNi0.5Mn1.5O4 Cathode Coated by Mn3O4

In this work the surface of LiNi\begin{document}$_{0.5}$\end{document}Mn\begin{document}$_{1.5}$\end{document}O\begin{document}$_{4}$\end{document} (LMN) particles is modified by Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document} coating through a simple wet grinding method, the electronic conductivity is significantly improved from 1.53\begin{document}$\times$\end{document}10\begin{document}$^{-7}$\end{document} S/cm to 3.15\begin{document}$\times$\end{document}10\begin{document}$^{-5}$\end{document} S/cm after 2.6 wt% Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document} coating. The electrochemical test results indicate that Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document} coating dramatically enhances both rate performance and cycling capability (at 55 ℃) of LNM. Among the samples, 2.6 wt% Mn\begin{document}$_{3}$\end{document}O\begin{document}$_{4}$\end{document}-coated LNM not only exhibits excellent rate capability (a large capacity of 108 mAh/g at 10 C rate) but also shows 78% capacity retention at 55 ℃ and 1 C rate after 100 cycles.     

Effects of Surface Defects on Adsorption of CO and Methyl Groups on Rutile TiO$_\text{2}$(110)

The interaction of reactants with catalysts has always been an important subject for catalytic reactions. As a promising catalyst with versatile applications, titania has been intensively studied for decades. In this work we have investigated the role of bridge bonded oxygen vacancy (O\begin{document}$_\textrm{v}$\end{document}) in methyl groups and carbon monoxide (CO) adsorption on rutile TiO\begin{document}$_2$\end{document}(110) (R-TiO\begin{document}$_2$\end{document}(110)) with the temperature programmed desorption technique. The results show a clear different tendency of the desorption of methyl groups adsorbed on bridge bonded oxygen (O\begin{document}$_\textrm{b}$\end{document}), and CO molecules on the five coordinate Ti\begin{document}$^{4+}$\end{document} sites (Ti\begin{document}$_{5\textrm{c}}$\end{document}) as the O\begin{document}$_\textrm{v}$\end{document} concentration changes, suggesting that the surface defects may have crucial influence on the absorption of species on different sites of R-TiO\begin{document}$_2$\end{document}(110).     

Fabrication of Melamine/Tb3+-Intercalated Polydiacetylene Nanosheets and Their Thermochromic Reversibility

Polydiacetylene (PDA) is one kind of the conjugated polymer with layered structure, which can serve as a host to accommodate the guest components through intercalation. In these intercalated PDAs, some of them were reported to have a nearly perfect organized structure and perform completely reversible thermochromism. Till now, these reported intercalated PDAs were made by only introducing a single component for intercalation. Here, we chose 10, 12-pentacosadiynoic acid (PCDA) as the monomer, of which the carboxyl-terminal groups can interact with either Tb\begin{document}$ ^{3+} $\end{document} ions or melamines (MAs). When the feeding molar ratio of PCDA, MA, and Tb\begin{document}$ ^{3+} $\end{document} ion was 3:267:1, only Tb\begin{document}$ ^{3+} $\end{document} ions were intercalated though excess MAs existed. Such Tb\begin{document}$ ^{3+} $\end{document}-intercalated poly-PCDA exhibited completely reversible thermochromism, where almost all the carboxyl groups interacted with Tb\begin{document}$ ^{3+} $\end{document} ions to form the nearly perfect structure. When the feeding molar ratio of PCDA, MA, and Tb\begin{document}$ ^{3+} $\end{document} ion was 3:267:0.6, both Tb\begin{document}$ ^{3+} $\end{document} ions and MAs were intercalated. There existed some defects in the imperfect MA-intercalated domains and at the domain boundaries. The MA/Tb\begin{document}$ ^{3+} $\end{document}-intercalated poly-PCDA exhibits partially reversible thermochromism, where the backbones near the defects are hard to return the initial conformation, while the rest, those at nearly perfect organized domains, are still able to restore the initial conformation.     

Delocalized \begin{document}$\pi_3^6$\end{document} Bond in OX\begin{document}$_2$\end{document} (X=Halogen) Molecules

OX\begin{document}$_2$\end{document} (X=halogen) molecules was studied theoretically. Calculation results show that delocalized \begin{document}$\pi_3^6$\end{document} bonds exist in their electronic structures and O atoms adopt the sp\begin{document}$^2$\end{document} type of hybridization, which violates the prediction of the valence shell electron pair repulsion theory of sp\begin{document}$^3$\end{document} type. Delocalization stabilization energy is proposed to measure the contribution of delocalized \begin{document}$\pi_3^6$\end{document} bond to energy decrease and proves to bring extra-stability to the molecule. These phenomena can be summarized as a kind of coordinating effect.     

Gd Doped Hollow Nanoscale Coordination Polymers as Multimodal Imaging Agents and a Potential Drug Delivery Carriers

Gd doped hollow nanoscale coordination polymers with multimodal imaging capabilities were synthesized by solvothermal method and further coated by silica layer. The \begin{document}$in$\end{document} \begin{document}$vitro$\end{document} tests demonstrated uncoated and silica-coated nanoprobes exhibit longitudinal relaxivities (\begin{document}$r_1$\end{document}) of 7.38 and 13.57 (mmol/L)\begin{document}$^{-1}$\end{document}\begin{document}$\cdot$\end{document}s\begin{document}$^{-1}$\end{document}, and transverse relaxivities (\begin{document}$r_2$\end{document}) of 180.6 and 304.8 (mmol/L)\begin{document}$^{-1}$\end{document}\begin{document}$\cdot$\end{document}s\begin{document}$^{-1}$\end{document}, showing fairly good dual T1&T2 contrast effects, and it also emits excellent multicolor fluorescence under laser beams of various wavelengths. With the combination of magnetic resonance imaging (MRI) (both T1 and T2) and fluorescence optical imaging (FOI), the nanoprobes could correlate preoperative diagnosis with intraoperative pathology. Furthermore, it also exhibits high drug loading capacity of 1166 mg/g and encapsulation efficiency of 83.29%, which makes it a potential platform as drug carriers. The MTT assay demonstrates the moderate toxicity of the NPs, and after the silica coating process, not only the MRI contrast effects but also the biocompatibility have been enhanced. The versatility of the highly integrated systems can make up for the limitations of each imaging modality and exhibit great potentials for cancer theranostics.     

Photochemistry of Potassium Ferrocyanide and its Reaction with Uridine 5′-monophosphate in Aqueous Solution under Ultraviolet Irradiation

The photochemical reaction of potassium ferrocyanide (K\begin{document}$ _4 $\end{document}Fe(CN)\begin{document}$ _6 $\end{document}) exhibits excitation wavelength dependence and non-Kasha rule behavior. In this study, the excited-state dynamics of K\begin{document}$ _4 $\end{document}Fe(CN)\begin{document}$ _6 $\end{document} were studied by transient absorption spectroscopy. Excited state electron detachment (ESED) and photoaquation reactions were clarified by comparing the results of 260, 320, 340, and 350 nm excitations. ESED is the path to generate a hydrated electron (e\begin{document}$ _{\rm{aq}}^{-} $\end{document}). ESED energy barrier varies with the excited state, and it occurs even at the first singlet excited state (\begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document}). The \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state shows \begin{document}$ {\sim} $\end{document}0.2 ps lifetime and converts into triplet [Fe(CN)\begin{document}$ _{6} $\end{document}]\begin{document}$ ^{4-} $\end{document} by intersystem crossing. Subsequently, \begin{document}$ ^{3} $\end{document}[Fe(CN)\begin{document}$ _{5} $\end{document}]\begin{document}$ ^{3-} $\end{document} appears after one CN\begin{document}$ ^{-} $\end{document} ligand is ejected. In sequence, H\begin{document}$ _{2} $\end{document}O attacks [Fe(CN)\begin{document}$ _{5} $\end{document}]\begin{document}$ ^{3-} $\end{document} to generate [Fe(CN)\begin{document}$ _{5} $\end{document}H\begin{document}$ _{2} $\end{document}O]\begin{document}$ ^{3-} $\end{document} with a time constant of approximately 20 ps. The \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state and e\begin{document}$ _{\rm{aq}}^{-} $\end{document} exhibit strong reducing power. The addition of uridine 5\begin{document}$ ' $\end{document}-monophosphate (UMP) to the K\begin{document}$ _{4} $\end{document}Fe(CN)\begin{document}$ _{6} $\end{document} solution decrease the yield of e\begin{document}$ _{\rm{aq}}^{-} $\end{document} and reduce the lifetimes of the e\begin{document}$ _{\rm{aq}}^{-} $\end{document} and \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state. The obtained reaction rate constant of \begin{document}$ ^{1} $\end{document}T\begin{document}$ _{\rm{1g}} $\end{document} state and UMP is 1.7\begin{document}$ {\times} $\end{document}10\begin{document}$ ^{14} $\end{document} (mol/L)\begin{document}$ ^{-1}\cdot $\end{document}s\begin{document}$ ^{-1} $\end{document}, and the e\begin{document}$ _{\rm{aq}}^{-} $\end{document} attachment to UMP is \begin{document}$ {\sim} $\end{document}8\begin{document}$ {\times} $\end{document}10\begin{document}$ ^{9} $\end{document} (mol/L)\begin{document}$ ^{-1}\cdot $\end{document}s\begin{document}$ ^{-1} $\end{document}. Our results indicate that the reductive damage of K\begin{document}$ _{4} $\end{document}Fe(CN)\begin{document}$ _{6} $\end{document} solution to nucleic acids under ultraviolet irradiation cannot be neglected.