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71.
UP Schlunegger M Stoeckli RM Caprioli 《Rapid communications in mass spectrometry : RCM》1999,13(18):1792-1796
An ion trap has been modified for the analysis of high mass ions generated by matrix-assisted laser desorption/ionization. Samples are deposited on a probe tip and introduced directly onto the hyperbolically shaped surface of one endcap. All three electrodes - both the endcaps and the ring electrode - are insulated so that the radio frequency (Rf) voltage may be applied to the center ring electrode and the inverted Rf voltage to the endcaps. By using low frequencies (below 100 kHz) and low amplitudes (below 200 V), high mass singly charged ions may be trapped and analyzed by a frequency sweep at constant amplitude. In the high mass range (60-160 kDa), this instrument showed good sensitivity, signal-to-noise ratios, and mass resolution. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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Silver J Marsh PJ Symons MC Svistunenko DA Frampton CS Fern GR 《Inorganic chemistry》2000,39(13):2874-2881
The crystal structure of the title compound is presented and shown to be one of a class of low-spin iron porphyrin complexes having a ground-state electronic configuration of (dxy)2(dxz)2(dyz)1. If their Fe-N bond lengths (average N-porphyrin plotted against average N-axial) are considered, this class of low-spin iron(III) porphyrins of general formula [Fe(III)Por(L)2]+X- and of 2B ground state is shown to be distinctly different crystallographically from a similar class of compounds with the same general formula but with a 2E or a (dxy)2(dxz,dyz)3 ground state. A third group of compounds with the same general formula have a (dxz,dyz)4(d)1 ground state and again are in a different region of the plot. Compounds showing intermediate properties can be forecast from the simple relationship presented in this work. The electron paramagenetic resonance data are shown to be dependent on the ground state, and those of configuration (dxy)2(dxz,dyz)3 and the 2B ground state obey a correlation previously suggested in the literature. 相似文献
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It is proved that the free energy of a system ofn-dimensional spins with Kac type potential is equal, in the infinite range zero strength limit, to the free energy of the corresponding Curie-Weiss system in which every spin interacts equally with every other spin. 相似文献
78.
Using the results of a configuration interaction calculation reported by Rosenberg and Shavitt, we derive an approximation
to the correlation energy which may be associated with the sum to infinite order of all linked diagrams involving singly-
and doubly-excited states. This result is compared with that obtained by calculation of the energy through third-order. The
fourth-order linked diagrams involving quadruply-excited states are computed. It is shown that there is a considerable degree
of cancellation between the fourth-order linked diagram energy terms involving doubly-excited intermediate states only and
those which contain quadruply-excited states. 相似文献
79.
A review of Tellurium-125 Mössbauer parameters is used to explain the colour of some organatellurium compounds in terms of the population of low energy conductance bands by non bonding electrons. 相似文献
80.
E. Träbert H. Hellmann P.H. Heckmann S. Bashkin H.A. Klein J.D. Silver 《Physics letters. A》1982,93(2):76-80
The transitions in Li-like Mg9+ ions have been investigated in beam-foil experiments at Bochum and Oxford. The finestructure intervals have been determined with a precision better than 3%, and the term multiplet separation has been determined to correspond to λ = (58.604 ± 0.005) nm. The finestructure results are compared with several calculations. 相似文献