نتایج جستجو برای: free electron

تعداد نتایج: 800571  

Journal: :Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1989

A green and efficient one pot, three component protocol for synthesis of naphthopyranopyrimidines by cyclocondensation of β-naphthol, aldehyde, and 6-amino-1,3-dimethyluracil using L-proline as a beneficial catalyst with high catalytic activity under solvent-free conditions at 100 °C is described. In this study, several types of aromatic aldehyde, containing electron-withdrawing groups as well ...

A green and efficient one pot, three component protocol for synthesis of naphthopyranopyrimidines by cyclocondensation of β-naphthol, aldehyde, and 6-amino-1,3-dimethyluracil using L-proline as a beneficial catalyst with high catalytic activity under solvent-free conditions at 100 °C is described. In this study, several types of aromatic aldehyde, containing electron-withdrawing groups as well ...

Journal: :Physical review accelerators and beams 2023

In this article, the concept of a recently funded R project for installation proof-of-concept cavity-based x-ray free electron laser (CBXFEL) demonstrator experiment at European XFEL facility is presented, with first results expected in 2024. It composed an cavity design backscattering geometry 133 m round trip length using cryogenically cooled diamond crystals. employs retroreflection to reduc...

Novel N-amino benzylthiolates were synthesized via multicomponent reaction of malononitrile, isothiocyanates and benzyl halides under conventional and solvent-free conditions. Various electron-donating and -withdrawing substitutes within both isothiocyanates and benzyl halides were used to demonstrate the efficiency of new methodology. A broad spectrum of antibacterial and antifungal activities...

Elham Tahanpesar, Vajihe Rohani Nejad

A rapid and chemoselective method for the N-formylation of structurally diverse anilines with formic acid using nanoalumina sulfonic acid (NASA) at 70oC under solvent-free condition has been developed. The catalyst was found to be compatible with different functional groups and the formylation proceeded smoothly with anilines bearing electron withdrawing as well as electron donating substituents.

1998
S. G. Oganesyan

A theory of transition free-electron laser ~FEL! driven by an electron bunch of finite longitudinal length is presented. It is shown that one can introduce concepts of a long, a short, and a very short bunch depending on the degree of correlation between the bunch effective length and the transition radiation formation length. It is obtained that a long Gaussian bunch produces an electromagneti...

2017
A. K. Shukla R. S. Dhaka S. W. D'Souza Sanjay Singh D. Wu S. R. Barman S. W. D’Souza

Using electron diffraction, we show that free-electron metals, such as sodium and potassium, form a highly regular quasiperiodic monolayer on the fivefold surface of icosahedral Al-Pd-Mn and that the quasiperiodicity propagates up to the second layer in sodium. Our photoelectron spectroscopy results show that the quasicrystalline alkali-metal adlayer does not exhibit a pseudogap near the Fermi ...

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