摘要:

The infrared spectrum of the anion dicyano[(dithionitrito-S) amido]nickelate(II), [Ni(CN)2(S2N2H)]−has been measured from 4000 to 200 cm−1. The absorption bands have been assigned by comparison to those of Ni(CN)42and Ni(S2N2H)2. Normal coordinate analysis on the Csplanar anion [Ni(CN)2(S2N2H)]−has been carried out using molecular parameters taken from X-ray data. Band assignments for the observed frequencies in this complex are in good agreement and show an average error of less than one half of one percent. In order to obtain good agreement between calculated and observed frequencies, it was necessary to modify the Urey-Bradley force field by adding selected interaction force constants. Its electronic spectrum is also discussed.

ISSN:0038-7010    

DOI:10.1080/00387018008064065

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Conformational energy differences have been determined from Raman spectra of the molecules ethylene glycol and 2-chloroethanol in DMSO and water. It was found that solvent effects on the relative stabilities of the gauche and trans rotamers of the two alcohols differ significantly. In addition, it was observed from spectra in the O-H stretching region that, unlike 2-chloroethanol, there is no significant intramolecular hydrogen bond formation in ethylene glycol in the neat liquid phase. Neither molecule was found to form intramolecular hydrogen bonds in either of the solvents studied.

ISSN:0038-7010    

DOI:10.1080/00387018008064066

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

In conventional and laser excited molecular fluorescence spectrometry,1,2the excitation scatter and luminescence from the blank have been shown to be the major factors controlling the limits of detection. However, because of their high intensity, an increase in sensitivity (signal/concentration) is often noted with laser excitation as compared with conventional sources. From theoretical calculations,3,4as well as experimental results,5pulsed source excitation with gated detection, using time resolution, can be used to improve the signal to noise ratio, S/N, in certain instances. Pulsed lasers are very well suited for these measurements because of their high intensities and short pulse widths.

ISSN:0038-7010    

DOI:10.1080/00387018008064067

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Presently, there are several techniques for measurement of fluorescence lifetimes of organic molecules. These techniques, reviewed by Ware,1can be divided into two basic groups, those based upon pulsed sources and those based on modulated sources and phase shift measurement. In the pulsed methods, repetitive, short pulse width, intense excitation pulses excite the fluorophor and the fluorescence decay is measured; the source temporal response must be deconvoluced from the fluorescence decay in order to evaluate the fluorescence signal and lifetime. Typical sources of excitation include nanosecond flashlamps and more recently nanosecond N2-laser (with or without a dye laser) and mode-locked lasers with picosecond pulse widths2-6. The modulated source phase shift methods,1involve sinusoidal excitation of the fluorophor and measurement of the phase shift between the modulated excitation source and the modulated flourescence. Because modulation frequencies are limited to approximately 20 MHz, fluorescence lifetimes are limited to ∼.1 ns and above. In addition, in the phase shift methods, only “one point” lifetimes are obtained, i.e., the entire fluorescence decay curve is not obtained.

ISSN:0038-7010    

DOI:10.1080/00387018008064068

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Three techniques for biological and agricultural sample preparation are compared. Commercially available inductively coupled argon plasma (ICAP) direct-reading spectrometers have been used to determine 29 major, minor, and trace elements in biological or agricultural samples following a nitric-perchloric acid digestion. At levels below the detection limit of the instrument, 21 other elements were found. The hydride generation-ICAP technique was employed for the determination of As, Bi, Sb, and Se in the same sample types.

ISSN:0038-7010    

DOI:10.1080/00387018008064069

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The decay of quantum system translated into the excited state depends on the manner of excitation and the system parametres as well [1]. In this case when the system was let to itself after the excitation its next development may be two-fold under the influence of spontaneous transitions of particles from the excited state to the ground state. The first one is the uncoherent spontaneous radiation. In this case all particles of the system are independently radiating. The total power of this radiation is the sum of spontaneous radiation powers of isolated particles. The second case is the coherent radiation, i.e. the particles are radiating into the coherence volume νωh= (c·T′2)3with a single phase (C is the field velocity in the medium andT′2is the phase relaxation time of the system). In the latter case the amplitude of the radiated field is propotional to the particle number N and the power is propotional to the square of particle number. However the second case is realized under the specified conditions only (such as the excitation pulse duration should be shorter than the phase relaxation times of the system and others). In this case the excited system let to itself these specific conditions may be realized (after a characteristic time). Under such conditions the probability W (W ∝N2) of the radiation of the one quantum of field by means of all excited particles is more than the probability of radiation of the one field quantum by means of the one particle. After that the whole system is transferred into the state from which it cannot get out (i.e. superradiant one [2]). In this state the probability of radiation process with the radiation power propotional to the square of particle number is more than anything other. However a two-fold development of the system may takes place. The first way is the free induction type process. And the second one is the avalanche process when the process of radiation proper is preparing the next states of the system and the radiation power is continiously increasing. Here we see the narrowing of the radiation spectrum and shortening of the radiation time in the last case [3]. As a rule the avalanche processes are formed when the excited state of the system is characterized by a certain degree of inversion.

ISSN:0038-7010    

DOI:10.1080/00387018008064070

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0038-7010    

DOI:10.1080/00387018008064064

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor