Search results for "oio"
showing 10 items of 152 documents
Theoretical study of the discrete and continuum spectrum of BeH
2008
The transition intensities supplied in this Letter are directly connected with a description of the discrete and continuum spectrum of BeH. An attempt to meet our goal requires the calculation of the absorption oscillator strengths of several transitions to Rydberg states of BeH, together with differential oscillator strengths which give rise to different dipole-allowed photoionization channels from the molecular ground state. The calculations have been performed with the molecular-adapted quantum defect orbital (MQDO) approach. Predictions of new spectroscopic data on BeH at energies where high Rydberg transitions can take place, including the continuum region of the spectrum have been mad…
Valence bands of poly(methylmethacrylate) and photoion emission in vacuum ultraviolet region
1992
Photoion and photoelectron yields were measured for poly(methylmethacrylate) in the photon energy region of 8–40 eV using synchrotron radiation. Further, the valence‐band structure was investigated with ultraviolet photoelectron spectra and valence effective Hamiltonian calculations. A significant difference was observed between the photon energy dependencies of photoion and photoelectron yields. The threshold energy for photoion emission was found to be 10.5 eV, while that for photoelectron emission was 8.5 eV, indicating holes created near the valence‐band top do not contribute to the ion emission. At the higher‐energy region, the ion emission efficiency was found to be enhanced in the ph…
Polymeric mesoions, 4. Synthesis of polymerizable mesoionic 4,6-dioxo-1,3-diazines derived from vinylbenzylmalonic acid
2000
Vinylbenzylmalonic acid (4) was condensed with N,N'-diphenylformamidine (5a), N,N'-diphenylacetamidene (5b), S-propyl-1,3-diphenylisothiourea (6) and anilinopyridine (7) in the presence of dicyclohexylcarbodiimide (DDC). The resulting new mesoionic monomers 8a-d were polymerized with 2,2'-azoisobutyronitrile (AIBN) as an initiator and dodecanethiol as a chain transfer agent. The low molecular weight model compounds 5-benzyl-pyrido[1,2-a]pyrimidine-2,4-dione (9a) and 5-hexadecyl-4,6-dioxo-1,3-diphenyl-2-hexadecylthio-1,3-diazine (9b) were prepared for X-ray diffraction analysis and comparison of spectrospical data.
MONITORAGGIO DEI PROCESSI EROSIVI NELL’AREA SPERIMENTALE DI SPARACIA
2014
Quantum Control in Atomic Systems
1999
We review a series of recent experiments demonstrating quantum control of atomic processes and products induced by the interaction of the atom with coherent bichromatic electromagnetic fields. Since the effects under consideration are electromagnetically induced, control is established through the field parameters i.e. frequency, amplitude and phase. The controlled processes include resonant and non resonant multiphoton ionization, autoionization, radiative decay in multiple continua (ionization branching ratios) and third harmonic generation.
Interpretation of absorption edges by resonant electronic spectroscopy: experiment and theory
2004
Abstract Resonant electronic spectroscopy consists in measuring a non-radiative decay process (Auger or autoionization process) excited with photon energies around an absorption edge. The resonant spectra carry information both on the nature of the electronic transitions near the absorption edge by scanning the very first empty orbitals above the Fermi level (through the absorption process), and, on the other hand, on the atomic electronic configuration through the lineshape of the observed decay process. In this paper, after a quick review of the pioneering works in this field, we show that resonant measurements and their theoretical modeling can be used to precisely interpret complex abso…
A study of the behaviour of 2,4-substituted thiosemicarbazides toward orthoesters: Formation of mesoionic compounds
1997
The reactions beetwen 2,4-disubstituted thiosemicarbazides and orthoesters in refluxing xylene led to the formation of the 1,2,4-triazoline-5-thione ring and to the 1,2,4-triazolium-5-thiolate ring. The formation of the mesoionic componds is due to rearrangement of the easily available 2,4-disubstituted thiosemicarbazides to 1,4-disubstituted thiosemicarbazides under the reaction conditions adopted. This method can be usefully used for the synthesis of mesoionic compounds, especially in the case of the 2-methyl-4-phenylthiosemicarbazide.
Iodofluorination of alkenes and alkynes promoted by iodine and 4-iodotoluene difluoride
2006
It was found that a mixt. of mol. iodine and 4-iodotoluene difluoride are useful to generate in situ the electrophilic iodine/nucleophilic fluorine (IF) couple that was able to add in a Markovnikov fashion and with prevalent anti-stereoselectivity to various alkenes and alkynes.
Un esperimento sulla distribuzione di energia in un sistema di particelle: il gas di elettroni termoionici
2009
La comprensione del concetto di distribuzione di energia di un insieme di particelle è un pre requisito di molti concetti rilevanti di termodinamica e meccanica statistica. Nella didattica della fisica a livello di scuola secondaria e di corsi introduttivi universitari, il ricavare la distribuzione di energia di un sistema di particelle è quasi esclusivamente affidato alla visualizzazione di simulazioni o alla trattazione teorica. Qui presentiamo un esperimento attraverso cui ricavare la distribuzione di energia degli elettroni emessi nel vuoto per effetto termoionico. Attraverso l’analisi di alcuni esperimenti storici sarà, mostrato come, con semplici accorgimenti, l’esperimento possa esse…