نتایج جستجو برای: spectra

تعداد نتایج: 108325  

Journal: :Chemical reviews 1997
J. J. Scherer J. B. Paul A. O'Keefe R. J. Saykally

The measurement of electronic spectra of supersonically cooled molecules and clusters is a widely used approach for addressing many problems in chemistry. The most established techniques for making such measurements are laser-induced fluorescence (LIF) and resonance-enhanced multiphoton ionization (REMPI), and both have been employed very successfully in a large number of studies. However, both...

2018
Isamu Akasaki Hiroshi Amano Shuji Nakamura

We have developed spectral models describing the electroluminescence spectra of AlGaInP and InGaN light-emitting diodes (LEDs) consisting of the Maxwell–Boltzmann distribution and the effective joint density of states. One spectrum at a known temperature for one LED specimen is needed for calibrating the model parameters of each LED type. Then, the model can be used for determining the junction...

1999
Aimee E. Curtright James K. McCusker

The spectroscopic and electrochemical properties of a series of four RuII polypyridyl complexes are reported. Compounds of the form [Ru(dmb)x(dea)3-x] (x ) 0-3), where dmb is 4,4′-dimethyl-2,2′-bipyridine and dea is 4,4′-bis(diethylamino)-2,2′-bipyridine, have been prepared and studied using static and time-resolved electronic and vibrational spectroscopies as a prelude to femtosecond spectrosc...

Journal: :Organic & biomolecular chemistry 2012
Xiao-Ting Liu Jing-Fu Guo Ai-Min Ren Zhong Xu Shuang Huang Ji-Kang Feng

N-arylpyrrole-based dyes possessing excellent opto-electronic properties are promising candidates for two-photon fluorescence labeling materials. The systematic investigation of novel N-arylpyrrole derivatives is of great importance for both fine-tuning electronic spectra and designing two-photon absorption (2PA) materials. We thoroughly studied influences of the π-conjugated center and N-subst...

1998
Adrian Görler Wolfram Gronwald Klaus-Peter Neidig Hans Robert Kalbitzer

t d i e s n i f t m s u A new tool, for the simulation of N or C edited 3D-NOESY– SQC spectra using the complete relaxation matrix approach, has een developed and integrated in the program AURELIA. This ool should be particularly useful for the fast and reliable comuter assisted assignment of 3D-NOESY–HSQC spectra by comaring back-calculated and experimental spectra in an iterative rocess. Fold...

Ahmad Reza Massah Mehran Ghiaci

The 1H and natural-abundance 13C-NMR spectra of 1-thiacyclooctan-3-one (1) have been measured from 25 to -100°C. Coalescence is observed in the 1H-NMR spectra of (1) at about -80°C, and attributed to ring inversion in a boat-chair conformation, which is the predominant conformation of (1). The free energy of activation (DG¹</s...

Anjali Krishnan Muhammed Ummathur, Perumpalli Ummer

The coupling of tetrazotised 1,8-diaminonaphthalene with 1,3-dicarbonyl compounds [acetylacetone,methylacetoacetate and acetoacetanilide] yielded a new series of tetradentate ligand systems. Analytical, IR,1H NMR and mass spectral data indicate that the compounds exist in the intramolecularly hydrogen bondeddihydrazone form. Dibasic tetradentate N2O2 coordination of these compounds in their [ML...

2002
Horst Kunkely Arnd Vogler

The electronic spectra and the photochemistry of the uranyl complexes UO2 (salophen) and UO2 (oxinate)2 with H2salophen = N,N'-bis(salicylidene)-o-phenylenediamine and oxine = 8hydroxyquinoline were studied. The excited state behavior of both complexes is determined by a low-energy salophen / oxinateÿ to U(VI) ligand-to-metal charge transfer (LMCT) state which is not luminescent but can be reac...

Journal: :The journal of physical chemistry. A 2006
H Abramczyk B Brozek-Płuska K Kurczewski M Kurczewska I Szymczyk P Krzyczmonik T Błaszczyk H Scholl W Czajkowski

Ultrafast time-resolved electronic spectra of the primary events induced in the copper tetrasulfonated phthalocyanine Cu(tsPc)4-) in aqueous solution has been measured by femtosecond pump-probe transient absorption spectroscopy. The primary events initiated by the absorption of a photon occurring within the femtosecond time scale are discussed on the basis of the electron transfer mechanism bet...

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