摘要:

This non-resonant optogalvanic effect caused by photoionization of the atoms lying at high excited levels is investigated in this work on the base of Neatoms in a hollow cathode glow discharge.

ISSN:0038-7010    

DOI:10.1080/00387019408003236

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The surface photo voltage (SPV) and photocurrent (PC) transients as a result of the excitation by the short high-intensity light pulses from semiconductor's intrinsic absorption spectral region are investigated in semi-insulating GaAs. It is shown that the mathematical convolution of SPV transients and arbitrary form double-pulse integrator (lock-in, double-boxcar) in a wide temperature range allows to receive the deep-level (DL) spectrum without the need to form electrical contacts to the crystal investigated. The use of such a procedure while scanning the crystal surface with a light spot at a temperature, corresponding to some DL maximum in the spectrum, makes possible the con tactless determination of this DL density distribution profile along the scanning direction.

ISSN:0038-7010    

DOI:10.1080/00387019408003237

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The paramagnetic contributions induced by TEMPOL soluble spin-label on gentiobiose carbon spin-lattice relaxation rates are analyzed. Selective effects in the β(1–6) glycosidic bond region were observed. The possibility of using soluble spin-label to determine the stereochemistry of the substrate-enzyme interaction was then explored.

ISSN:0038-7010    

DOI:10.1080/00387019408003238

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The electron transfer products of aromatic Schiff bases generated by reaction with alkali naphthalenides and electrochemically have been investigated by means of infrared spectroscopic technique. On the basis of the assigned nitrile group band frequencies and intensities in the measured infrared spectra, the anion radicals, dianions and carbanions of the compounds under investigation have been identified.

ISSN:0038-7010    

DOI:10.1080/00387019408003239

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The normal coordinate analysis of a model compound for Cu, Zn-SOD: [(dtma)CuImZn(dtma)]CIO4· 2.5H2O (where dtma = 4-diethylenetriamineacctate; Im = imidazolate) has been carried out by using a Urey-Bradley force field. According to the molecular structure, 240 internal coordinates were established and 174 theoretical vibrational frequencies were calculated. Due to introducing an appropriate set of internal coordinates and force constants in the course of calculation, the calculated frequencies agree well with the observed values, with the average difference 4.40cm−1and the maximum deviation 24.2cm−1between them, although the structure of the title compound is complicated. Some structural and spectral properties are here discussed.

ISSN:0038-7010    

DOI:10.1080/00387019408003240

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The 60 MHz1H NMR spectra of the methyl ester derivative,1, of the imidazolinone herbicide, imazapyr, have been studied in CDC13at 28±1° (as the racemic free base) with the added achiral lanthanide shift reagent (LSR), tris(6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (III),2, for spectral simplification, and with the chiral LSR, tris[3-(heptafluoropropylhydroxymethylene)-(+)-camphorato]europium(III),3, to induce enantiomeric shift differences (ΔΔδ). An additional series of runs employed the chiral LSR, tris[3-(trifluoromethylhydroxymethylene)-(+)-camphorato]europium(III),4. Substantial lanthanide-induced shifts (LIS) were observed with each added LSR. Added 3. appeared to elicit large ΔΔδ magnitudes for H-6 on the pyridine ring (alpha to nitrogen), whereas 4. caused smaller ΔΔδ values for the quaternary and isopropyl methyls on the imidazolinone ring.

ISSN:0038-7010    

DOI:10.1080/00387019408003241

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The temperature dependence of the chemical shift for protons of CH2 groups franked to D2O was supported experimentally. The linear correlation between these parameters was established for all animal tissues examined in vivo.

ISSN:0038-7010    

DOI:10.1080/00387019408003242

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Abstract - A series of dirhodium tetracarboxylate complexes, containing triphenylphosphine as axial ligand was investigated by electronic and Raman spectroscopy, aiming to detect the influence of electronic effects of the carboxylate substituents on the v1[v(RhRh)] and v2[v(RhO)] Modes. When pairs of complexes with similar molecular weights are compared, as in the case of the cyclopentanecarboxylate and trifluoroacetate complexes, the striking difference in the inductive character of the two species results in substantial shifts of the v1and v2modes as a consequence of variations in the corresponding force constants rather than a simple mass effect as previously observed for non-substituted rhodium-carboxylates.

ISSN:0038-7010    

DOI:10.1080/00387019408003243

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

There are numerous clinical situations, such as hyperthermia cancer therapy, under which body temperature has to be accurately evaluated. Magnetic Resonance Imaging presently offers the best set of non-invasive methods for body temperature mapping, including diffusion imaging, relaxation time measurement, magnetization transfer contrast and chemical shift spectroscopic imaging. The basic NMR parameters involved in each are first analyzed. The role of temperature in their physical variation is then presented and finally the different practical MRI methods are briefly discussed. In the present slate of available technology and for basic physical reasons, the T 1 method appears the best compromise at low and medium magnetic field in a limited temperature range. Chemical shift could be theoretically more promising but strictly depends from the homogeneity and stability of the magnet and will be available only at high or very high field.

ISSN:0038-7010    

DOI:10.1080/00387019408003244

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Abstract: The vibrational spectra of crystalline anhydrous copper (II) propionate and butyrate were studied by FT-IR spectroscopy. A detailed assignment of the spectra of both compounds is presented and discussed. It is shown that the presence of two non-equivalent sets of carboxylate ligands within the crystals gives rise to several band splittings, which are particularly evident in those bands ascribable to normal modes involving predominantly the -CβH3or -CβH2-fragments. In addition, the vibrational assignments made for the studied molecules are shown to be very useful to help understanding the much more complex spectra of long chain copper carboxylates.

ISSN:0038-7010    

DOI:10.1080/00387019408003245

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor