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61.
62.
Analytical potential-energy surfaces have been constructed for the ground and the first excited states of HeH2. The functions fit ab initio MRD CI calculations with standard deviations of 0.05 and 0.13 eV for the ground and the excited surface respectively. Classical trajectory calculations for collisions of 4Hc with HD(B 1Σu+, υ = 3, J = 2) at the temperature T = 297 K yields the electronic quenching cross section σQ = 6.5 A2 and the vibrational cross section σ3→2 = 3.8 A2. The results are in qualitative agreement with the experimental values of Fink, Akins and Moore. 相似文献
63.
The electronic structure of the ground and low-lying states of the diatomic fluorides TiF, VF, CrF, and MnF was examined by multireference and coupled cluster methods in conjunction with extended basis sets. For a total of 34 states we report binding energies, spectroscopic constants, dipole moments, separation energies, and charge distributions. In addition, for all states we have constructed full potential curves. The suggested ground state binding energies of TiF(X (4)Phi), VF(X (5)Pi), CrF(X (6)Sigma(+)), and MnF(X (7)Sigma(+)) are 135, 130, 110, and 108 kcal/mol, respectively, with first excited states A (4)Sigma(-), A (5)Delta, A (6)Pi, and a (5)Sigma(+) about 2, 3, 23, and 19 kcal/mol higher. In essence all our numerical findings are in harmony with experimental results. For all molecules and states studied it is clear that the in situ metal atom (M) shows highly ionic character, therefore the binding is described realistically by M(+)F(-). 相似文献
64.
Criteria for aerosol synthesis of soft-agglomerate, hard-agglomerate, or even nonagglomerate particles are developed on the basis of particle sintering and coalescence. Agglomerate (or aggregate) particles are held together by weak, physical van der Waals forces (soft agglomerates) or by stronger chemical or sintering bonds (hard agglomerates). Accounting for simultaneous gas phase chemical reaction, coagulation, and sintering during the formation and growth of silica (SiO2) nanoparticles by silicon tetrachloride (SiCl4) oxidation and neglecting the spread of particle size distribution, the onset of hard-agglomerate formation is identified at the end of full coalescence, while the onset of soft-agglomerate formation is identified at the end of sintering. Process conditions such as the precursor initial volume fraction, maximum temperature, residence time, and cooling rate are explored, identifying regions for the synthesis of particles with a controlled degree of agglomeration (ratio of collision to primary particle diameters). 相似文献
65.
Temitope T. Abiola Nazia Auckloo Jack M. Woolley Christophe Corre Stphane Poigny Vasilios G. Stavros 《Molecules (Basel, Switzerland)》2021,26(24)
Plants, as with humans, require photoprotection against the potentially damaging effects of overexposure to ultraviolet (UV) radiation. Previously, sinapoyl malate (SM) was identified as the photoprotective agent in thale cress. Here, we seek to identify the photoprotective agent in a similar plant, garden cress, which is currently used in the skincare product Detoxophane nc. To achieve this, we explore the photodynamics of both the garden cress sprout extract and Detoxophane nc with femtosecond transient electronic absorption spectroscopy. With the assistance of liquid chromatography-mass spectrometry, we determine that the main UV-absorbing compound in garden cress sprout extract is SM. Importantly, our studies reveal that the photoprotection properties of the SM in the garden cress sprout extract present in Detoxophane nc are not compromised by the formulation environment. The result suggests that Detoxophane nc containing the garden cress sprout extract may offer additional photoprotection to the end user in the form of a UV filter booster. 相似文献
66.
67.
Dror Bar-Natan Stavros Garoufalidis Lev Rozansky Dylan P. Thurston 《Israel Journal of Mathematics》2000,119(1):217-237
We conjecture an exact formula for the Kontsevich integral of the unknot, and also conjecture a formula (also conjectured
independently by Deligne [De]) for the relation between the two natural products on the space of uni-trivalent diagrams. The
two formulas use the related notions of “Wheels” and “Wheeing”. We prove these formulas ‘on the level of Lie algebras’ using
standard techniques from the theory of Vassiliev invariants and the theory of Lie algebras. In a brief epilogue we report
on recent proofs of our full conjectures, by Kontsevich [Ko2] and by DBN, DPT, and T. Q. T. Le, [BLT].
This paper is available electronically 相似文献
68.
Abigail L. Whittock Jack M. Woolley Nazia Auckloo Christophe Corre Vasilios G. Stavros 《Molecules (Basel, Switzerland)》2022,27(7)
Mycosporine-like amino acids are a prevalent form of photoprotection in micro- and macro-organisms. Using a combination of natural product extraction/purification and femtosecond transient absorption spectroscopy, we studied the relaxation pathway for a common mycosporine-like amino acid pair, usujirene and its geometric isomer palythene, in the first few nanoseconds following photoexcitation. Our studies show that the electronic excited state lifetimes of these molecules persist for only a few hundred femtoseconds before the excited state population is funneled through an energetically accessible conical intersection with subsequent vibrational energy transfer to the solvent. We found that a minor portion of the isomer pair did not recover to their original state within 3 ns after photoexcitation. We investigated the long-term photostability using continuous irradiation at a single wavelength and with a solar simulator to mimic a more real-life environment; high levels of photostability were observed in both experiments. Finally, we employed computational methods to elucidate the photochemical and photophysical properties of usujirene and palythene as well as to reconcile the photoprotective mechanism. 相似文献
69.
Stavros Iliadis 《Topology and its Applications》2008,156(1):76-82
In the present paper it is proved the existence of topologically universal elements in some classes of mappings and classes of G-spaces generalizing some results from [S.D. Iliadis, Universal Spaces and Mappings, North-Holland Math. Stud., vol. 198, Elsevier, 2005] and [S.D. Iliadis, Universal Borel mappings and Borel actions of groups, Topology Appl., in press, doi:10.1016/j.topol.2007.05.029]. 相似文献
70.
Ardie Walser Stavros Demos Michael Etienne Roger Dorsinville 《Optics Communications》2004,240(4-6):417-421
The presence of strong nonlinear absorption has been observed in laser modified fused silica. Intensity-dependent transmission measurements using 355, 532 and 1064 nm laser pulses were performed in pristine polished regions in fused silica substrates and in locations that were exposed to dielectric breakdown. The experimental results suggest that multiphoton absorption is considerably stronger in the modified regions compared to pristine sites and is strongly dependent on the excitation wavelength. 相似文献