Convergence of the distribution functions for wormlike chains

The Daniels-type distribution functions of the end-to-end distance of three-dimensional and two-dimensional wormlike chains are obtained to terms of order t^?10, by an operational method with use of a digital computer, where t is the ratio of the total chain contour length to the Kuhn segment length in three-dimensional cases and of the contour length to the persistence length in two-dimensional cases. The convergence of the ring-closure probability and the mean reciprocal distance is examined on the basis of these distribution functions. A similar study of the moment-based distribution functions is also made.     

Fluorescence quenching of versatile fluorescent probes based on strongly electron-donating distyrylbenzenes responsive to aromatic chlorinated and nitro compounds, boronic acid and Ca(2+)

The fluorescence quenching behavior of two distyrylbenzenes (DSBs) newly prepared bearing strongly electron-donating groups was investigated. Several chlorinated and nitro compounds quench the fluorescence of both DSBs with various efficiencies depending on the electron-withdrawing properties; the strongly electron-withdrawing compound, such as 2,4,5-trichlorophenol and 2,4-dinitrofluorobenzene, effectively diminish the fluorescence intensities of the DSBs. The fluorescence quenching was also detected in the interaction between the azacrown DSB and phenylboronic acid, while the fluorescence recovers by adding triethylamine. These quenching phenomena are attributed to the photo-induced electron transfer (PET) process. On the other hand, the azacrown DSB selectively interacts with Ca(2+) to decrease its fluorescence intensity, but the DSB with the dimethylamino groups did not. These results suggest a potential use of these types of compounds as sensors for strongly electron-withdrawing substances and a suitable metal cation.     

SmI2-promoted Reformatsky-type reaction and acylation of alkyl 1-chlorocyclopropanecarboxylates

In the presence of HMPA in THF, highly stereoselective SmI(2)-promoted substitutions of alkyl 1-chlorocyclopropanecarboxylates 1 using various ketones, aldehydes (Reformatsky-type reaction), and acyl chlorides (acylation) proceeded to give trans-adducts (2 or 5) in good to high yield with excellent trans-stereoselectivity (trans-add/cis-add = > 99/1). The Reformatsky-type reaction of 1 with aldehydes and unsymmetrical ketones proceeded with moderate diastereoselectivity (re-face-adduct/si-face-adduct = 60/40-75/25).     

Optical noise reduction for dc-removed coaxial holographic data storage

A method of reconstructing positive and negative images from Fourier holograms recorded without the dc components is demonstrated by use of a coaxial holographic storage system. Reconstructed images are obtained by adding a phase-modulated dc component of the signal beam on reading. Contrast reversal of the reconstructed images can be achieved by reversing the readout reference pattern. This method can realize not only optical noise reduction but also less consumption of the dynamic range of the recording medium, potentially contributing to increasing the number of multiplexed holograms.     

Stationary rescaled pulse in dispersion-managed comblike profiled fiber for highly efficient and high-quality optical pulse compression

A stationary rescaled pulse (SRP) exists in a dispersion-managed comblike profiled fiber (DM-CPF) that consists of alternate concatenations of normal-dispersion highly nonlinear fiber and single-mode fiber. Numerical analysis reveals that the newly found SRP exhibits a nearly Gaussian temporal profile with a small amount of pedestal in spite of a relatively large compression ratio. We apply the SRP propagation to optical pulse compression based on DM-CPF and demonstrate highly efficient and high-quality optical pulse compression. Using a three-step DM-CPF, we experimentally show that a 2.6 ps width input pulse is successfully compressed to a nearly Gaussian pulse having the width of 0.39 ps and the peak-to-pedestal ratio of 19.3 dB.     

Retracted: Mass analysis by Ar‐GCIB‐dynamic SIMS for organic materials

Generally, dynamic secondary ion mass spectrometry (SIMS) has been mainly used as one of the most powerful tools for inorganic mass analysis. On the other hand, an Ar gas cluster ion beam (GCIB) has been developed and spread as a processing tool for surface flattening and also a projectile for time‐of‐flight (ToF) SIMS. In this study, we newly introduced an Ar‐GCIB as a primary ion source to a commercially available dynamic SIMS apparatus, and investigated mass spectra of amino acid films (such as Arginine and Glycine) and polymer films (Polyethylene: PE and Polypropylene: PP) as organic model samples. As a result, each characteristic fragment peak indicating the original molecular organic structure was observed in the acquired mass spectra. In addition, their own molecular ions of the amino acids were also clearly observed. Mass spectra of PE/PP blended‐polymer films acquired using Ar‐GCIB‐dynamic SIMS could be identified between pure PE and PE:PP = 1:3 mixture by applying principal component analysis (PCA).     

Crucial dependence of chemiluminescence efficiency on the syn/anti conformation for intramolecular charge-transfer-induced decomposition of bicyclic dioxetanes bearing an oxidoaryl group

Thermally stable rotamers of bicyclic dioxetanes bearing 6-hydroxynaphthalen-1-yl (anti-5a and syn-5a), 3-hydroxynaphthalen-1-yl (anti-5b and syn-5b), and 5-hydroxy-2-methylphenyl groups (anti-5c and syn-5c) were synthesized. These dioxetanes underwent TBAF (tetrabutylammonium fluoride)-induced decomposition accompanied by the emission of light in DMSO and in acetonitrile at 25 °C. For all three pairs of rotamers, the chemiluminescence efficiency Φ(CL) for anti-5 was 8-19 times higher than that for syn-5, and the rate of CTID (charge-transfer-induced decomposition) for anti-5 was faster than that for syn-5. The chemiluminescence spectra of the rotamers for 5a and 5c, respectively, were different. This discrepancy in the chemiluminescence spectra between rotamers can presumably be attributed to the difference in the structures of de novo keto imide anti-14 and syn-14 in an excited state, which inherit the structures of the corresponding intermediary anionic dioxetanes anti-13 and syn-13. The important difference in chemiluminescence efficiency between anti-5 and syn-5 is discussed from the viewpoint of a chemiexcitation mechanism for CTID of oxidophenyl-substituted dioxetane.