摘要:

Semiempirical molecular orbital calculations have been shown to predict double minima potential surfaces which are not confirmed by further experimental or theoretical evidence.1These same techniques predict barriers to internal rotation which are not only in large error but may not even follow the experimental trends.2These discrepancies offer a large decrease in self confidence for the application of these techniques to molecular systems where direct experimental evidence is not available, and these are often the circumstances where one wants a theory to be used. Therefore, our research group is in the process of reparameterizing the procedure INDO3to yield barriers to internal rotation, bond angles, and bond lengths within reliable confidence limits. During this process of determining new parameters we have observed that some sets of parameters will also remove the anomalous energy minima predicted by the original INDO parameters. To illustrate this we consider in this paper the molecule CO2.

ISSN:0038-7010    

DOI:10.1080/00387017308065458

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The proton NMR spectra of transhydroxy-L-proline at 90 and 250 MHz are analysed by computer simulation. A new long range coupling constant is displayed. The sign of all coupling constants is given. Some structural implications are discussed. A position for the carboxylic plane is proposed.

ISSN:0038-7010    

DOI:10.1080/00387017308065459

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

Over the past several years studies of laser induced infrared fluorescence have been reported.1-5These studies were carried out on about fifty compounds. Many of the compounds absorbed the laser radiation and fluoresced strongly. Some of these compounds; such as methane, nitromethane, chloroform, carbon disulfide, nitrous oxide, and sulfur dioxide; did not appreciably absorb at the laser wavelength (10.6 microns). Nevertheless it was found that they fluoresced, although, at a relatively low intensity.

ISSN:0038-7010    

DOI:10.1080/00387017308065460

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

A new low-lying 1Σg+state of the nitrogen molecule was recently predicted from ab initio calculations of the first 102 states which result from nitrogen atoms in the4S,2D and2P states (1). The calculated spectroscopic constants for this new state seemed to fit well with the ones that could be estimated from the unidentified bands at 6895.5 Å and 8937.0 Å reported by Lofthus (2,3). Since spectrograms taken at moderate resolution already were available in the wavelenght region of interest, no new experiments at high resolution were initiated and a search for these bands was made. It was soon found that the wave numbers listed by Lofthus to a certain extent coincided with the listings given by Dieke and Heath (4) for theOP12andOP23satellite branches of the (1, 0) and (3, 0) bands of the B3Σg- A3Σu+transition of N2. No other bands which could be related to the predicted1Σg+state were found in this region.

ISSN:0038-7010    

DOI:10.1080/00387017308065461

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

For several 1,3-diaryl- and 1-alkyl-3-aryltriazenes, infraared evidence of tautomerism III has been given;1,2in their ir spectra, in fact, these compounds generally show two separate N-H stretching bands. The relative intensities of these bands are influenced by the substituents,1,2It was recognized,how ever, that the tautomeric equilibrium constants KTcannot be determined with accuracy by ir bands intensity measurements as the molar extinction coefficients of forms I and II are not known.1

ISSN:0038-7010    

DOI:10.1080/00387017308065462

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

There has been a continuing interest in the structure of water and of aqueous solutions, and many studies have employed spectroscopic techniques. These have frequently involved absorption spectroscopy in the near-IR range, and Raman scattering. In general, however, the normal IR range has been but little used except for studies of HDO-containing solutions, and the region near 3500 cm−1of the intense H2O absorption has been almost completely avoided. Transmission techniques have been exclusively employed with absorption spectroscopy. Internal reflection spectroscopy (IRS) techniques have been employed to examine aqueous solutions, but the emphasis was placed on studying the solute rather than the solvent. Also, the solute concentrations which had been employed in transmission studies have been rather high. We now suggest the feasibility of carrying out structural studies of aqueous solutions by using IRS techniques to record spectra in the IR range, employing solutions of relatively low concentrations. For example, the lowest concentration of aqueous HCl solution examined by Ackermann1was 2.5 M by transmission techniques in the 4000-1100 cm−1range; in contrast, using IRS, the perturbations of the O-H stretching and deformation bands of H2O could be observed with 0.1 M HCl.

ISSN:0038-7010    

DOI:10.1080/00387017308065463

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The theoretical consideration of the sponteneous emission of γ-gravitons by excited nuclei lead us to the conclusion about the principle possibility of γ-graviton detection from cosmic and laboratory sources. The γ-graviton astronomy and geophysics can give new information about cosmic and geophysical processes.

ISSN:0038-7010    

DOI:10.1080/00387017308065464

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor

摘要:

The EPR spectrum of the triplet ground state dimer di-μ-(pyridine N-oxide)bis[bisnitrato(pyridine N-oxide)copper(II)] has been reported recently1. Of the very few triplet ground state copper(II) dimers with resolved metal hyperfine structure2,3, the EPR spectrum of this complex is most complete. Previously, the analysis of the spectra of triplet ground state copper(II) complexes, in order to extract magnetic parameters, has been made using the equations reported by Wassermanet al.4The best magnetic parameters should be obtained from a simulation of the experimental spectrum. We wish to report here the computer simulation of the EPR spectrum of a powdered sample of [Cu(II) (PYO)2(NO3)2]2.

ISSN:0038-7010    

DOI:10.1080/00387017308065465

出版商:Taylor & Francis Group    

年代:1973

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:10.1080/00387017308065457

出版商:Taylor & Francis Group    

年代:1973

数据来源: Taylor