Trapping dynamics of diindenoperylene (DIP) in self-assembled monolayers using molecular simulation

All-atom Molecular Dynamics simulation methods employing a well-tested intermolecular potential model, MM3 (Molecular Mechanics 3), demonstrate the propensity for diindenoperylene (DIP) molecules to insert between molecules of a self-assembled monolayer (SAM) during a deposition process intended to grow a thin film of this organic semiconductor molecule onto the surface of self-assembled monolayers. The tendency to insert between SAM molecules is fairly prevalent at normal growth temperatures and conditions, but is most strongly dependent on the density and the nature of the SAM. We posit the existence of an optimal density to favor surface adsorption over insertion for this system. DIP is less likely to insert in fluorinated SAMs, like FOTS (fluorooctatrichlorosilane), than its unfluorinated analog, OTS (octatrichlorosilane). It is also less likely to insert between shorter SAMs (e.g., less insertion in OTS than ODTS (octadecyltrichlorosilane)). Very short length, surface-coating molecules, like HDMS (hexamethyldisilazane), are more likely to scatter energetic incoming DIP molecules with little insertion on first impact (depending on the incident energy of the DIP molecule). Grazing angles of incidence of the depositing molecules generally favor surface adsorption, at least in the limit of low coverage, but are shown to be dependent on the nature of the SAM. The validity of these predictions is confirmed by comparison of the predicted sticking coefficients of DIP at a variety of incident energies on OTS, ODTS, and FOTS SAMs with results obtained experimentally by Desai et al. (2010) [23]. The simulation predictions of the tendency of DIP to insert can be explained, in large part, in terms of binding energies between SAM and DIP molecules. However, we note that entropic and stochastic events play a role in the deposition outcomes. Preliminary studies of multiple deposition events, emulating growth, show an unexpected diffusion of DIP molecules inserted within the SAM matrix in a clear attempt of the DIP molecules to aggregate together.     

压气机转子内流场的三维LDV测量

激光多普勒测速仪（LDV）的应用日益变得广泛，由于环境条件、物理和几何上的可达性以及流动的复杂性，使人们在每个具体应用中，需要对仪器参数合理地设置和实验装置全面地考虑．通过对一个轴流压气机转子尖区内流场的反复测试，比较精细的流动结构被揭示出来．这里所阐述的LDV测量技术，在其它方面的应用中，也具有一定的普遍意义．     

A comparative study of the PIV and LDV measurements on a self-induced sloshing flow

Particle Imaging Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) measurements on a self-induced sloshing flow in a rectangular tank had been conducted in the present study. The PIV measurement result was compared with LDV measurement result quantitatively in order to evaluate the accuracy level of the PIV measurement. The comparison results show that the PIV and LDV measurement results agree with each other well in general for both mean velocity and fluctuations of the velocity components. The average disagreement level of the mean velocity between PIV and LDV measurement results was found to be within 3% of the target velocity for the PIV system parameter selection. Bigger disagreements between the PIV and LDV measurement results were found to concentrate at high shear regions. The spatial resolution and temporal resolution differences of the PIV and LDV measurements and the limited frames of the PIV instantaneous results were suggested to be the main reasons for the disagreement.     

Fluorescence Labelling of DNA by Carboxylic Polypyridyl-Ru Complexes Containing bpy and DIP Ligands: A Study Revisited

The coordination complexes (DIP)₂Ru(CH₃bpyCOOH) and (DIP)₂Ru(COOHbpyCOOH), where DIP and bpy are diphenylphenanthroline and bispyridine, have been recently proposed as fluorescent markers of nuclear DNA (Musatkina et al., J. Inorg. Biochem. 101:1086–1089, 2007), but no DNA binding investigation and no quantitative fluorescence evaluations had been done. Both complexes, as well as the smaller ones with bpy’s in place of DIP’s, have been investigated here by spectroscopic DNA titrations (UV–vis absorption, fluorescence, circular dichroism) and by in vitro cellular studies (flow cytometry and fluorescence imaging). Contrary to previous reports, neither the carboxylic function nor the more extended DIP ligand ensures any appreciable binding to DNA. This is clearly illustrated by the appearance of an isosbestic point of a second kind and by the proportionality of the fluorescence maximum intensity to the absorbance at the excitation wavelength. Above all, the lack of enhanced fluorescence in the presence of DNA definitively rules out the use of such complexes as DNA markers. Moreover, there is no detectable nuclear uptake. However, the fluorescent complexes with the DIP ligands, especially (DIP)₂Ru(CH₃bpyCOOH), are massively incorporated into the cytoplasm while preserving cell integrity, which could suggest other types of biological application.     

Cl+HN3产生NCl(a1Δ)和NCl(b1∑)的实验研究

 对利用微波放电直接解离Cl₂生成Cl, Cl与HN₃反应生成NCl(a^1Δ )和NCl(b^1∑)的过程进行了实验研究。得到了较强的NCl(a^1Δ 和NCl(b^1∑)自发辐射光谱,考察了Cl₂流量和He/Cl₂配比对NCl(a^1Δ 和NCl(b^1∑)生成的影响。发现对于一定的He流量,Cl₂流量对NCl(a^1Δ 和NCl(b^1∑)生成的影响存在一最佳范围,而最佳He/Cl₂配比不是一定值,而是随He流量升高而变大,在实验所考察的He流量范围（5~40 L/min）内,最佳He/Cl ₂配比在30∶1~100∶1之间。     

自适应滤波技术在激光多普勒测速仪中的应用

激光多普勒测速仪检测系统提取的光电信号中存在较大的噪声信号。为了消除这些噪声干扰, 提高激光多普勒测速仪的测量精度,提出一种新的信号处理方法,将最小均方差自适应滤波技术应用于激光多普勒测量中,利用多普勒信号和噪声信号的统计特性,以最小均方误差估计为准则,最大程度地滤除噪声信号。阐述了最小均方差自适应滤波算法的基本原理,在MATLAB平台上将其应用于理想正弦信号进行仿真,并将其应用于实测多普勒信号的处理中。仿真和实验均表明,该技术可以有效抑制激光多普勒测量中的多频率噪声的干扰,大大提高多普勒信号的信噪比和测量精度,为设计高精度的激光多普勒测速仪创造了条件。     

Measurements of velocity distributions in the deformation zone in cold rolling by a scanning LDV

Experimental determination of the velocity distribution in the deformation zone is of significant importance to investigate the metal flow in both conventional and asymmetrical rolling processes. In this paper, a scanning laser Doppler velocimetry (LDV) system, designed for measuring the velocity distributions in the deformation zone in plate rolling is reported. The LDV used for the rolling process is briefly described and then the scanning mechanism based on beam displacement by a rotating transparent plate is introduced. The relationship among the scanning distance, the beam-cross angle of the LDV system and the rotating angle of the plate is established. The scanning LDV was first tested with a rotating disk and then applied in the rolling process. The test results have demonstrated the feasibility of the scanning LDV.     

Real-time X-ray diffraction measurements of structural dynamics and polymorphism in diindenoperylene growth

We investigate the temperature-dependent polymorphs in diindenoperylene (DIP) thin films on sapphire and silicon oxide substrates using in situ X-ray scattering. On both substrates the DIP unit cell is very similar to the high-temperature phase of bulk crystals, with the substrate stabilising this structure well below the temperature where a phase transition to a low-temperature phase is observed in the bulk. Lowering the substrate temperature for DIP growth leads to a change in molecular orientation and an additional polymorph appears, with both these effects being more pronounced on sapphire as compared to silicon oxide. Using real-time reciprocal-space mapping we observe an expansion of the in-plane unit cell during DIP growth, which may be due to changes in molecular orientation as well as strain in the first monolayers. Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.     

Detection of laser induced dielectric breakdown in water using a laser doppler vibrometer

This study is focused on exploring the feasibility of an all-optic surface scanning method in determining the size and position of a submerged, laser generated, optoacoustic (OA) source. The optoacoustic effect in this case was generated when the absorption of a short electromagnetic pulse in matter caused a dielectric breakdown, a plasma emission flash and a subsequent acoustic wave. In the experiment, a laser pulse with λ = 1064 nm and 12 ns pulse length was aimed at a volume of deionized water. When the laser beam was focused by a f = 16 mm lens, a single dielectric breakdown spot occurred. When a f = 40 mm was used several breakdowns in a row were induced. The breakdowns were photographed using a double shutter camera. The acoustic wave generated by the dielectric breakdowns were detected at a point on the water surface using a laser Doppler vibrometer (LDV). First, the LDV signal was used to calculate the speed of sound with an accuracy of 10 m/s. Secondly, the location and length of the dielectric breakdown was calculated with an accuracy of 1 mm. The calculated position matched the breakdown location recorded by a camera. The results show that it is possible to use LDV surface measurements from a single spot to determine both the position and length of the OA source as well as the speed of sound in the medium. Furthermore, the LDV measurements also show a secondary peak that originates from the OA source. To unravel the origin and properties of this interesting feature, further investigations are necessary     

Two-dimensional laser Doppler velocimeter using polarized beams and 90° phase shift for discrimination of velocity direction

A laser Doppler velocimeter (LDV) for two-dimensional velocity measurement using a simple optical configuration without any optical modulator is proposed. The structure using polarized beams and the 90° phase shift of the reference beam is used to discriminate the direction of velocity. The analytical relation among beat frequencies and velocity components is derived and the characteristics of the proposed LDV are simulated. The simulation results indicate that the direction of velocity can be discriminated by the proposed LDV as well as the magnitudes of the components of the velocity.     

Spectrophotometric Studies and Analytical Applications of the Complexes of Fe(III), Ni(II) and Cu(II) with Some 4-Amino-Antipyrene Azo Derivatives

Extensive study of composition, stability constants and optimum conditions of Fe(III), Nl (II) and Cu(II) complexes with four azo compounds based on 4 - amlnoantlpyrene are done. The coloured complexes formed, at the optimum. conditions mentioned, can be successfully used In the mlcrodetermlnation of metal Ions In synthetic solutions as well as In Incoloy 800 alloy. The method described Is rapid, sensitive, highly accurate and reproducable.     

Combined “Fluorescence” LDV (FLDV) and PDA Technique for Non‐ambiguous Two Phase Measurements Inside the Spray of a SI‐Engine

Laser velocimetry measurements in the vicinity of reflecting surfaces are still a major problem in many fluid mechanical applications such as measuring close to walls or wall film surfaces, respectively. Moreover, in any kind of two phase flow an unambiguous separation of the gas and the liquid phase is of particular interest. Commonly used techniques like Phase Doppler Analyzers (PDA) with size discrimination are limited to two phase flows where the smallest particle of the dispersed phase is significantly larger than the seeding particles. This condition can rarely be fulfilled in technically relevant spray/air systems for instance in automobile engines or gas turbines. One of the most promising approaches to overcome this problem is a correct phase discrimination using fluorescent tracer particles for the gas phase. In this paper different laser based velocimeters have been compared using the spray of a gasoline injection nozzle as a typical example. The working principle of the “fluorescence” LDV (FLDV) will be explained in detail. Moreover, the quality of the fluorescence signals and of the standard bursts received from Mie‐scattering particles will be compared. Finally, the capabilities of combined FLDV and PDA measurements inside the spray of a SI‐engine at unsteady conditions will be presented. The pros and cons of this technique will be discussed against the background of discriminatory two phase PIV measurements applied to the same spray.     

Cross-correlation Doppler global velocimetry (CC-DGV)

A flow velocimetry method, cross-correlation Doppler global velocimetry (CC-DGV), is presented as a robust, simplified, and high dynamic range implementation of the Doppler global/planar Doppler velocimetry technique. A sweep of several gigahertz of the vapor absorption spectrum is used for each velocity sample, with signals acquired from both Doppler-shifted scattered light within the flow and a non-Doppler shifted reference beam. Cross-correlation of these signals yields the Doppler shift between them, averaged over the duration of the scan. With presently available equipment, velocities from 0 ms⁻¹ to over 3000 ms⁻¹ can notionally be measured simultaneously, making the technique ideal for high speed flows. The processing routine is shown to be robust against large changes in the vapor pressure of the iodine cell, benefiting performance of the system in facilities where ambient conditions cannot be easily regulated. Validation of the system was performed with measurements of a model wind turbine blade boundary layer made in a 1.83 m by 1.83 m subsonic wind tunnel for which laser Doppler velocimetry (LDV) measurements were acquired alongside the CC-DGV results. CC-DGV uncertainties of ±1.30 ms⁻¹, ±0.64 ms⁻¹, and ±1.11 ms⁻¹ were determined for the orthogonal stream-wise, transverse-horizontal, and transverse-vertical velocity components, and root-mean-square deviations of 2.77 ms⁻¹ and 1.34 ms⁻¹ from the LDV validation results were observed for Reynolds numbers of 1.5 million and 2 million, respectively. Volumetric mean velocity measurements are also presented for a supersonic jet, with velocity uncertainties of ±4.48 ms⁻¹, ±16.93 ms⁻¹, and ±0.50 ms⁻¹ for the orthogonal components, and self-validation done by collapsing the data with a physical scaling.     

钒氧酞菁(VOPc)与钒酞菁(VPc)分子的扫描隧道显微镜图像模拟

利用第一性原理方法模拟了自由钒氧酞菁(VOPc)和钒酞菁(VPc)分子的扫描隧道显微镜(STM)图像,与实验观察结果相当符合.理论STM图像都显示出亚分子内结构,外围呈四叶状.其主要差异表现在VOPc分子中心处的钒氧离子在STM图像中为一空洞,而在VPc分子的STM图像中钒离子为突起的亮斑.通过分析VOPc和VPc分子的电子结构,对模拟结果给出自洽的理论解释.造成两者图像显著不同的物理原因是VPc分子在费米能级附近有明显含dz2成分的分子轨道,导致钒离子在STM图像中央为突起的亮斑.而在VOPc分子中dz2分态密度峰位由于氧原子的加入使之远离费米能级,使STM不能“看到”VOPc分子中钒氧离子. 关键词： 钒氧酞菁 钒酞菁 STM图像模拟 电子结构     

C1＋HN3产生NCl（a^1Δ）和NCl（b^1∑）的实验研究

对利用微波放电直接解离Cl2生成Cl,Cl与HN3反应生成Ncl（a^1Δ）和NCl(b^1∑）的过程进行了实验研究,得到了较强的Ncl(a^1Δ）和NCl（b^1∑）自发辐射光谱,考察了Cl2流量和He/Cl2配比对NCl(a^1Δ)和NCl(b^1∑）生成的影响,发现对于一定的He流量,Cl2流量对NCl(a^1Δ)和NCl(b^1∑）生成的影响存在一最佳范围,而最佳He/Cl2配比不是一定值,而是随He流量升高而变大,在实验所考察的He流量范围（5－40L/min)内,最佳He/Cl2配比在30：1－100：1之间。     

Real-time observation of structural and orientational transitions during growth of organic thin films

We study kinetically controlled orientational and structural transitions of molecular thin films during growth in situ and in real time, using diindenoperylene (DIP) as an example. By time-resolved surface-sensitive x-ray scattering (out of plane and in plane), we follow the organic molecular beam deposition of DIP on silicon oxide, on stepped sapphire, and on rubrene as an organic model surface. We identify transitions for the few-monolayer (ML) regime, as well as for thick (several 10's of ML) films. We show that the differences in the interaction of DIP with the substrate change the thickness as well as temperature range of the transitions, which include (transient) strain, subtle changes of the orientation, as well as complete reorientation. These effects should be considered rather general features of the growth of organics, which, with its orientational degrees of freedom, is qualitatively different from growth of inorganics.     

Sizing Large Hollow Micro-Balloons with the phase doppler interferometer

A combined theoretical and experimental study has been conducted to evaluate the effectiveness of using large, hollow micro-balloons as LDV seed particles. The study has focused on the ability of phase Doppler systems to size hollow microballoons, the ability of large micro-balloons to respond to high frequency spatial and temporal flow field variations, and the overall advantages and disadvantages of using large microballoons instead of conventional LDV seed particles, such as very small water droplets or polystyrene latex (PSL) particles. This paper discusses the development of a theoretical phase Doppler response model for stratified spheres, the experimental facility, and the theoretical and experimental results.     

NCl(a1Δ)/I（2P3/2）传能体系的实验研究

 利用微波放电Cl₂/He等离子体作为Cl源，对反应NCl(a¹Δ) + I(²P_3/2)→NCl(X³Σ) + I(²P_1/2)进行了实验研究，得到了较大的I(²P_1/2)自发辐射荧光信号，检测到NCl(a¹Δ，b¹Σ)自发辐射荧光光谱在存在少量I(²P_1/2)下发生的显著变化，其中NCl(a¹Δ)自发辐射荧光信号降低，同时由于I(²P_1/2)的作用，NCl(b¹Σ)自发辐射荧光信号大幅度增加。在考察各反应气体流量对I(²P_1/2)自发辐射荧光信号的影响时发现，在本次实验条件下，各种气体的最佳流量：He为1～4mmol/s, I₂为0.01～0.03mmol/s, Cl₂为1.0mmol/s左右,而HN₃流量略大于Cl₂流量时信号升高幅度开始变缓，约为Cl₂流量的两倍时信号不再有显著的变化。     

Developments in laser Doppler accelerometry (LDAc) and comparison with laser Doppler velocimetry

This paper outlines the principles and early development of an interferometric technique for remote measurement of vibration acceleration — laser Doppler accelerometry (LDAc). One of the key advantages of LDAc over laser Doppler velocimetry (LDV) is its ability to measure extremely high vibration accelerations and shocks, effectively without limit, and this point is expanded upon in the paper. Early LDAc development showed how unwanted, velocity-dependent optical beats could occur on the photodetector but novel use of a frequency shifting device, whose primary purpose was for direction discrimination, was successful in isolating the required acceleration-dependent beat. A problem remained in the rate at which the velocity-dependent and acceleration-dependent beats broadened during target motion. In a further development, it was possible to 'select’ a back reflection to produce a velocity-dependent beat that was NOT modulated in the presence of target motion. The acceleration-dependent beat could then be demodulated and preliminary results are given to demonstrate this outcome.     

A shell-model treatment of (0+1) ħω states in A=4–16 nuclei (II)

The results of spurious-state free calculations in a complete (0+1)?ω model space on theA=4–16 nuclei are presented. The calculated spectra as well as electromagnetic properties of the normal- and nonnormal-parity states are compared with the experimental data. In general good agreement is obtained, while in particular the magnetic-dipole and electric-quadrupole moments are very well reproduced. The present results for the normal-parity states are similar to those of Cohen and Kurath. Several nonnormalparity states expected at rather low excitation energies and properties of very neutronrich nuclei have not been observed experimentally so far.