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Molar extinction coefficients of some carbohydrates viz. l-arabinose (C5H10O5), d-glucose (C6H12O6), d-mannose (C6H12O6), d-galactose (C6H12O6), d(-) fructose (C6H12O6) and maltose (C12H24O12) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a
narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter
polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying
within experimental uncertainty. Within concentration ranges studied, Beer-Lambert law is obeyed very well. 相似文献
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25.
Coherent dynamics of multiphoton excitation of molecular vibrational modes by subpicosecond IR laser pulses differs greatly from that of picosecond pulse excitation. The resonance response of a molecule is primarily determined by the power broadening rather than the laser carrier frequency. Selective excitation of high vibrational levels is possible with the use of subpicosecond pulses. 相似文献
26.
V. V. Paramonov V. A. Petrosyan V. I. Slovetskii A. A. Fainzil'berg Yu. G. Dubovik 《Russian Chemical Bulletin》1976,25(8):1628-1631
Conclusions Data on electrolysis in strongly acidic media have shown that, contrary to accepted belief, reduction of the un-ionized form of trinitromethane proceeds through C-N bond rupture rather than through breakage of the nitro group N-O bond.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1725–1729, August, 1976. 相似文献
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Selective control over the vibrational excitation and space quantization of the dissociation fragments by optimally designed
linearly polarized and shaped infrared (IR) laser pulses of the picosecond (ps) and subpicosecond duration is demonstrated
by means of quantum-dynamical simulations within the Schr?dinger wave-function formalism for a three-dimensional (3-D) model
of HONO2 in the ground electronic state, wherein the OH and the ON single-bond stretches are explicitly treated, together with the
bending angle between them, on the basis of the ab initio defined 3-D potential-energy surface and dipole function. The high-lying
zeroth-order vibrational states of the OH bond are prepared selectively both below and above the dissociation threshold of
the ON single bond, and demonstrate a quasi-periodic oscillatory behaviour, manifesting intramolecular vibrational energy
redistribution (IVR) on the picosecond timescale. Selective breakage of the ON single bond in HONO2 with more than 97% probability is demonstrated, along with control of the space quantization of the dissociation fragments:
the OH fragments rotating clockwise, OH(c), and anticlockwise, OH(a), are prepared selectively, with the OH(a)/OH(c) branching
ratio being as high as 10.975. The results obtained show that optimally designed strong and short IR-laser pulses can compete
against IVR and manipulate vibrational excitation and dissociation of polyatomic molecules.
Received: 3 November 1999 / Published online: 13 July 2000 相似文献
29.
Paramonov PB Lyuksyutov SF Mayevska OV Reagan MA Umemura K Tobari H Hara M Vaia RA Juhl S 《Langmuir : the ACS journal of surfaces and colloids》2006,22(15):6555-6561
Chemically induced rearrangements of amphifunctional molecules have been demonstrated using strong nonuniform electric fields (10(8)-10(10) V m(-1)) induced in the vicinity of nanoscale asperities. Electrostatic interactions utilizing these rearrangements of alkylthiolates assembled on Au(111) result in the nanopatterning of raised nanostructure (1.5-9 nm high, 15-100 nm wide) arrays on a second time scale by manipulating an atomic force microscope (AFM) tip above the monolayer. It is suspected that, as a result of the oxidative cleavage initiated by a weak bias of the tip, the S end of the alkylthiolate chain carrying a sulfenium cation is attracted to the (lifting) tip, forming bi- and higher-layer structures in the vicinity of the tip apex. Stabilization of the multiple-layered structures is accomplished via mutual attraction and entanglement of hydrocarbon chains. The rearrangements suggest a novel and general approach for nanoscale architecture in self-assembled systems. 相似文献
30.
Physics of Particles and Nuclei Letters - The initial part (IP) of a compact pulsed proton linac with an output energy of ?230 MeV is intended for the formation and acceleration of a beam... 相似文献