Integrative fitting of absorption line profiles with high accuracy,robustness, and speed

The principle of the integrative evaluation of absorption line profiles relies on the numeric integration of absorption line signals to retrieve absorber concentrations, e.g., of trace gases. Thus, it is a fast and robust technique. However, previous implementations of the integrative evaluation principle showed shortcomings in terms of accuracy and the lack of a fit quality indicator. This has motivated the development of an advanced integrative (AI) fitting algorithm. The AI fitting algorithm retains the advantages of previous integrative implementations—robustness and speed—and is able to achieve high accuracy by introduction of a novel iterative fitting process. A comparison of the AI fitting algorithm with the widely used Levenberg–Marquardt (LM) fitting algorithm indicates that the AI algorithm has advantages in terms of robustness due to its independence from appropriately chosen start values for the initialization of the fitting process. In addition, the AI fitting algorithm shows speed advantages typically resulting in a factor of three to four shorter computational times on a standard personal computer. The LM algorithm on the other hand retains advantages in terms of a much higher flexibility, as the AI fitting algorithm is restricted to the evaluation of single absorption lines with precomputed line width. Comparing both fitting algorithms for the specific application of in situ laser hygrometry at 1,370 nm using direct tunable diode laser absorption spectroscopy (TDLAS) suggests that the accuracy of the AI algorithm is equivalent to that of the LM algorithm. For example, a signal-to-noise ratio of 80 and better typically yields a deviation of <1 % between both fitting algorithms. The properties of the AI fitting algorithm make it an interesting alternative if robustness and speed are crucial in an application and if the restriction to a single absorption line is possible. These conditions are fulfilled for the 1,370 nm TDLAS hygrometry at the aerosol and cloud chamber aerosol interactions and dynamics in the atmosphere (AIDA)—a unique large-scale facility to study atmospheric processes. The robustness of the AI fitting algorithm has been validated for typical AIDA conditions encompassing strong transmission fluctuations during the formation of droplet or ice clouds inside AIDA. Under these conditions, the stability of the AI algorithm remained virtually unaffected. Thus, the AI algorithm presents an alternative technique for a fast, reliable, and accurate online data evaluation of the humidity measurements at AIDA.     

Sufficient Conditions for Uniform Bounds in Abstract Polymer Systems and Explorative Partition Schemes

We present several new sufficient conditions for uniform boundedness of the reduced correlations and free energy of an abstract polymer system in a complex multidisc around zero fugacity. They resolve a discrepancy between two incomparable and previously known extensions of Dobrushin’s classic condition. All conditions arise from an extension of the tree-operator approach introduced by Fernández and Procacci combined with a novel family of partition schemes of the spanning subgraph complex of a cluster. The key technique is the increased transfer of structural information from the partition scheme to a tree-operator on an enhanced space.     

Complete coverage of reduced graphene oxide on silicon dioxide substrates

Reduced graphene oxide(RGO) has the advantage of an aqueous and industrial-scale production route. No other approaches can rival the RGO field effect transistor platform in terms of cost(相似文献   

Encapsulation of Luminescent Homoleptic [Ru(dpp)3]2+‐Type Chromophores within an Amphiphilic Dendritic Environment

A new series of homoleptic metallodendrimers has been synthesized through ruthenium‐metal complexation by dendritically modified bathophenanthroline ligands. The presence of hydrophilic oligo(ethylene glycol) groups on the surface of the monodisperse metal complexes enabled the solubilization of all of the fractal species in a wide range of solvents, including water. The specific properties of all of these compounds have been systematically investigated by using photophysical techniques as a function of the generation number. Accordingly, the encapsulation of the highly luminescent [Ru(dpp)₃]²⁺‐type (dpp=4,7‐diphenyl‐1,10‐phenanthroline) core unit within a dendritic microenvironment creates a powerful means to shield the center from dioxygen quenching. This shielding effect, as exerted on the phosphorescent ruthenium‐derived center, is reflected by enhanced emission intensities and extended excited‐state lifetimes that are close to the highest values reported so far, even in an air‐equilibrated aqueous medium. Interestingly, when inspecting the largest dendritic assembly, that is, the third‐generation assembly, significant drops in emission quantum yields and lifetimes are observed. This anomalous behavior has been attributed to the folding of the branches towards the luminescent core.