摘要:

The available data on the microwave spectrum of methylenimine are critically reviewed for information applicable to radio astronomy. Molecular data such as rotational constants, centrifugal distortion parameters, hyperfine coupling constants, and dipole moments are tabulated. A detailed centrifugal distortion calculation has been carried out for the most abundant isotopic form of this molecule, H212C14NH. Transitions have been predicted and tabulated for the frequency range 100 MHz to 300 GHz. All predicted transitions include 95 percent confidence limits; error limits have been reported for all measured transitions.

ISSN:0047-2689    

DOI:10.1063/1.3253110

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A detailed analysis of specific heat data in the critical region of magnetic solids is presented. An inverse power law, whose strength is measured by the exponent &agr;, is used to describe the temperature dependence of the magnetic specific heat. Other parameters used include the power law coefficientA, the critical temperatureTc, and a constant background termB. Advanced techniques of data analysis suitable for estimation of nonlinear parameters and their errors under conditions of realistically weighted experimental data were used to obtain the dependence of &agr;,Tc,A, andBon the range of data points included in the fit. Those exponents and parameters that provide the best overall fit to the data have been found. Literature references to 49 experiments from 1935 to 1971 are given. We present in tabular form the values of &agr;,A, andBfor 24 different magnetic crystals. With some exceptions, the best fits to the data suggest that in the temperature range studied the magnetic specific heat is not symmetric; the exponent &agr; depends on the range of data included in the fit, varies widely from material to material, and in many cases is definitely negative below the critical temperature; and that there is little evidence that the asymptotic region is being adequately sampled by experiment. These results have the implication that until such time as we can adequately account for departures from the expected sharp peak in the data atTc(data rounding) and corrections to asymptotic scaling, then comparisons between magnetic specific heat experiments and lowest order scaling predictions are to this date still tenuous.

ISSN:0047-2689    

DOI:10.1063/1.3253111

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The available information, up to mid‐1972, for the rate constants of a series of gas phase chemical reactions has been evaluated critically. For each reaction, relevant thermodynamic data are presented and values for the equilibrium constant expressed in mathematical form. Kinetic data are presented in tabular and graphical form together with a discussion of the pertinent details. Recommended rate constant values are presented wherever possible with suggested error limits. The reactions considered involve the species H, O, C, N, S, OH, HS, S2, CS, SO, HSO2, NH2, NH3, NO, N2O, NO2, N2, O2, O4, N2, O2, O3, H2, H2O, SO2, SO3, CS2, OCS, H2S, and CO. Particular emphasis is given to reactions involving sulfur chemistry. The best available data for these reactions have been summarized in a table at the end of the paper. An appendix discussing the available evaluations and review articles published since 1960 also has been included to publicize these sources of either evaluated data or of extensive reference bibliographies.

ISSN:0047-2689    

DOI:10.1063/1.3253112

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Atomic transition probabilities for about 750 forbidden spectral lines for elements of the iron group, specifically V, Cr, Mn, Fe, Co, and Ni, have been critically evaluated and compiled using all available literature sources. The selection of the spectra and elements has been made primarily according to their astrophysical importance. The data are presented in separate tables for each element and stage of ionization, and for each ion the data are arranged according to multiplets. For each line within a multiplet the transition probability for spontaneous emission is listed along with the standard spectroscopic designation, the wavelength, the statistical weights, and the energy levels of the upper and lower states. In addition, the estimated accuracy and the source are indicated. In short introductions which precede the individual tables for the ions the main justifications for the choice of the adopted data and for the accuracy rating are discussed. A general introduction contains a detailed discussion of the critical factors entering into the calculations. It also includes detailed comparisons of calculated data with astrophysical observations and a few laboratory results, which serve as a valuable indication for the validity of the estimated accuracies.

ISSN:0047-2689    

DOI:10.1063/1.3253113

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The compilations of fundamental vibrational frequencies of molecules previously published in the NSRDS—NBS publication series and in this journal are here extended to 55 additional molecules. Selected values of the fundamental vibrational frequencies are given for each molecule, together with observed infrared and Raman spectral data and citations to the original literature. The selection of vibrational fundamentals has been based on careful studies of the spectral data and comprehensive normal‐coordinate analyses. An estimate of the accuracy of the selected values is included. The tables provide a convenient source of information for those who require vibrational energy levels and related properties in molecular spectroscopy, thermodynamics, analytical chemistry, and other fields of physics and chemistry.

ISSN:0047-2689    

DOI:10.1063/1.3253114

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Energy band gaps are tabulated for elemental and binary compound semiconductors and insulators reported in 723 references. The method of measurement, transition, type of sample, and other pertinent information are included for each entry. The determinations believed to be the most reliable are indicated.

ISSN:0047-2689    

DOI:10.1063/1.3253115

出版商:AIP    

年代:1973

数据来源: AIP