摘要:

Infrared and Raman spectra were obtained for 2, 3, 3-trimethyl-1-butene, and a vibrational assignment was made with the aid of normal coordinate calculations. Molecular mechanics calculations were also made to determine molecular parameters of the stable conformation. Values for the force constants of a forty-one parameter modified valence force field were obtained that will be used for other 2-methyl-1-alkenes that contain substituted methyl groups.

ISSN:0038-7010    

DOI:10.1080/00387019408006646

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Extensive study of composition, stability constants and optimum conditions of Fe(III), Nl (II) and Cu(II) complexes with four azo compounds based on 4 - amlnoantlpyrene are done. The coloured complexes formed, at the optimum. conditions mentioned, can be successfully used In the mlcrodetermlnation of metal Ions In synthetic solutions as well as In Incoloy 800 alloy. The method described Is rapid, sensitive, highly accurate and reproducable.

ISSN:0038-7010    

DOI:10.1080/00387019408006647

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Polarized Raman scattering spectra and surface enhanced Raman scattering spectra have been recorded from a thin film of a stretched polystyrene and from an adsorbed thin layer of polystyrene on silver surface, respectively. Comparison of intensities of the Raman line near 786 cm−1indicates that the aromatic rings are perpendicular to the surface in polystyrene which deposited onto silver from a very dilute solution.

ISSN:0038-7010    

DOI:10.1080/00387019408006648

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The paper proposes a new approach to the determination of moleculare force fields from observed vibrational frequencies for the case, that observed frequencies are only given in more or less sharp expectation ranges (intervals). Starting from a physically reasonable force constant space, we determine force fields so that the calculated eigenfrequencies are near by the experimental ones. However, in contrast to classical least squaress methods, we will model the uncertainty expressed by the statement “near by” with special triangle functions where the experimental values stand in the head of the triangles. In the sense of the fuzzy set theory, these functions are interpreted as membership functions. Within the force constant space we carry out Normal Coordinate Analyses in the usual way and determine a force field so that the eigenfrequencies have the least possible deviation from the experimental values. The deviation is evaluated with the help of the triangle membership functions. Hence, the selected force field with least deviation is called a fuzzy-optimal one. The water molecule is selected as a model case, because its least-squares force field is precisely known. Following the Born-Oppenheimer-Approximation, we treat all water isotopes in the same manner and select fuzzy-optimal force fields so that the evaluations for each water isotope are approximately similar and as high as possible. We will see that the fuzzy approach is always applicable, even if the assumptions for application of least squares methods are failed. This is a main advantage of the fuzzy method.

ISSN:0038-7010    

DOI:10.1080/00387019408006649

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Radiative lifetimes of 8p2P3/1(15.3 ns) and nf2F (7f2F5/2- 24.7 m. 7f2F7/2- 5.5 ns, 8f2F7/2- 48.5 ns, 8f2F5/2- 47.0 ns) levels of Hg+have been measured employing delayed coincidence method. The dependencies of radiative lifetimes vs effective principal quantum number for np2P3/2and np2F7/2series are non linear.

ISSN:0038-7010    

DOI:10.1080/00387019408006650

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The near UV absorption, steady-state polarized fluorescence excitation and time–-resolved fluorescence emission spectra of indole in argon matrix are reported. The absorption maxima of the four lowest singlet transitions were identified at 35095 cm−1(also the S1, 00–0 band), 37650 cm−1(S2,0), 47415 cm−1(S3,0), and 51680 cm−1(S4,0). No distinct 0–0 band of the second transition was identified but the linearly polarized, steady-state fluorescence excitation spectrum indicates an onset of weak S2,0bands on the blue side of the S1,00–0 peak (35095 + 400 cm−1). Only one fluorescence emission component, of 4.9±0.2 ns, was obtained by excitation over the S1, 00–0 + 565 cm−1to S1,00–0 - 245 cm−1domain. The reported data strongly suggest the1Lb−1A1and1La−1A1assignment for the lowest and next lowest transitions, respectively.

ISSN:0038-7010    

DOI:10.1080/00387019408006651

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Abietic acid, which is the terpene acid component of natural colophony, was irradiated at above 300 nm in the presence of benzophenone and a colloidal platinum catalyst. The expected product of dehydroabietic acid was formed to the extent of 81 %, hydrogen generation occurred to a negligibly small amount. The hydrogen generation, even as a by-product of an aimed solar photochemical product, do not carry appreciable importance because the hydrogen yield is too low to have any value on use.

ISSN:0038-7010    

DOI:10.1080/00387019408006652

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The absorption, excitation and fluorescence spectra of the fluorescein dianion (FL2−) in N, N-Dimethylformamide (DMF)/water (H2O) and Dimethylsulphoxide (DMSO)/H2O solvent mixtures have been investigated. It is found that the absorption λmaxand emission maxima EX,naxare both hypsochromic shifted when the H2O content in the solvent mixtures increases. However, the shoulder peaks λsremain constant at 483. 5nm within the range of H2O mole fraction, x= 0 to 0. 518 in a DMF/H2O solvent mixture and at 484. 4nm within the range, x=0 to 0. 304, in a DMSO/H2O mixture. Further increases in H2O content, cause a hypsochromic shift in λs. The molar energies for the electronic transition from the ground state (S0) to S1, the first excited singlet state, (ET(1)) and to S2, the 2nd excited singlet state, (ET(2)) of FL2−in the solvent mixtures are also plotted against x. Linear straight lines and intersection points are observed at x=0. 73 for ET(1) and at x=0. 51 for ET(2) in the DMF/H2O mixture and at x=0. 71 for ET(1) and at x=0. 31 & 0. 69 for ET(2) in the DMSO/H2O mixture. Hydrogen-bonding stabilization effects are used to explain the above observations. The variation in relative fluorescence quantum yields of S1and S2of FL2−with x in the aprotic solvent-H2O mixtures to FL2−in pure aprotic solvent are determined and discussed.

ISSN:0038-7010    

DOI:10.1080/00387019408006653

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The He-broadened half-widths of 65 lines of Phosphine in the range of 2200–2400 cm−1have been measured at 293 K by means of a Fourier Transform spectrometer at 0. 006 cm−1resolution. For several experimental conditions related to PH3and He pressures we used 2 and 5 mm path-length. The broadening coefficients derived using a non-linear fitting technique are reported.

ISSN:0038-7010    

DOI:10.1080/00387019408006654

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The effect of solvent on the electronic spectra of some fasciolici-dal o–-hydroxylbenzenesulfonanilides is examined and discussed. It is revealed that in solution these compounds exist in both intramolecular hydrogen bond form and intermolecular hydrogen bond form occurring between solute and solvent molecule. In solutions containing large amount of apolar aprotic solvents such as dioxane, compounds studied are mainly intramolecular hydrogen bond form and exhibit a weak transition band which is presumably attributed to the transition of n-electrons of oxygen atom in the intramolecular hydrogen bonded six-membered ring of the compounds.

ISSN:0038-7010    

DOI:10.1080/00387019408006655

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor