摘要:

It was shown1–4that a most significant parameter characterizing radiationless electron transitions is the Franck-Condon factor F. In the present paper the Franck-Condon factor for the [sgrave]-ν transition will be considered, i.e. the transition between the vibrational quantum numbers of a higher and lower electronic states respectively.

ISSN:0038-7010    

DOI:10.1080/00387017208064677

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

In a previous paper1it has been shown that the harmonic oscillator model is incapable of providing sufficiently large Franck-Condon factors F(E) if realistic parameter values are to be used. In consequence the calculated rate constants v=i/τ of radiationless electronic transitions at E ∼ 3 ev do not agree with those obtained experimentally. It has further been shown that this problem can be solved by using the Morse oscillator model. The calculations, however, were confined to a specific, though frequently encountered, case of the general expression for the Franck-Condon factor of a Morse oscillator, viz., the case of a small parameter =, where δω1-ω, ω1and ω being vibrational frequencies in a higher and lower electronic states respectively, Δr = rei- reis the difference of coordinates of oscillator equilibrium positions in the respective electronic states mentioned, and α is a parameter of the Morse curvefor the lower electronic state.

ISSN:0038-7010    

DOI:10.1080/00387017208064678

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A number of experimental results have been recently made available on the temperature dependence of lifetimes of excited states of polyatomic molecules in condenced1–6and gaseous phases. The dependence was shown to be quite substantial in experiments with both fluorescence5,6and phosphorescence1–4temperature quenching. The decay-rate constant of electronic excitation is 1/τ′ = β + 1/τ, where b is determined by radiative processes and is but slightly temperature-dependent5,6. As for the rate constant 1/τ of radiationless electronic transitions, it might be the very parameter that governs the temperature dependence of 1/τ.

ISSN:0038-7010    

DOI:10.1080/00387017208064679

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

In our previous work1a formula is presented for the rate constantof a radiationless electronic transition as a function of temperature τ for the Morse oscillator model. The formula was derived for the particular case of a sufficiently small parameter. In the above formulavo=v(T= o),Ais a constant, Δω = ω1- ω1where ω and to are vibrational frequencies in the higher and lower electronic states respectively, and α is a parameter of the Morse curvewhere re1is analogous to rebut refers to an excited electronic state. The expression for probabilityv(T) can be used to account for a number of experimental results on the temperature quenching of luminescence. However, the probability expression is valid for low values ofonly, and, besides, in practice the usual Arrhenius dependence of v(τ) is much more frequent than the one indicated by the expression. Therefore, it seems desirable to analyze the Morse oscillator model for a more or less arbitrary value of.

ISSN:0038-7010    

DOI:10.1080/00387017208064680

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The utility of the inert gas shielded nitrous oxide-acetylene flame for the determination of arsenic and selenium by atomic absorption spectrometry has been demonstrated elsewhere1. The low background absorbance of the fuel-rich, 50 mm path-length flame (ca4 and 5% at the As 193.7 and Se 196.0 nm lines respectively) permits the attainment of detection limits which are equal to, or somewhat superior to, those obtainable with the air-acetylene flame. The AAS sensitivity (that concentration producing 1% absorption), however, is decreased; this is the result of the shorter path length of this flame compared to that employed for air-acetylene (100 mm) and the lower concentration of analyte produced in the larger volume of gas used to support the flame.

ISSN:0038-7010    

DOI:10.1080/00387017208064681

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Experimental and theoretical (INDO-MO) studies of n → transitions have been carried out for seven symmetric diazines. In all cases, there is very good agreement between the theoretical predictions and experimental observations on the symmetry of the lowest energy n→* singlet state.

ISSN:0038-7010    

DOI:10.1080/00387017208064682

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Substituted N,N-dimethylformamidines (I, R′˭H) exhibit temperature-dependent pmr spectra which are associated with hindered rotation about the C-N bond. The rotational barrier is attributed to the contribution of a zwitterion of type II.1,2,3

ISSN:0038-7010    

DOI:10.1080/00387017208064683

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The photochemistry of simple, alicyclic enones has been the subject of extensive study during the last decade, and this area is the subject of a recent review.2Investigation of the crossed-cycloaddition of cyclopentenone to a variety of alkenes was undertaken in our laboratory in connection with a program of synthesis of precursors for nonbenzenoid, aromatic systems. In a previous report3we described the photoaddition of cyclopentenone to cycloheptene, from which four products were identified.

ISSN:0038-7010    

DOI:10.1080/00387017208064684

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The interaction of a gravitational wave (G.W.) with substances causes periodical changes of their density. These changes may be fixed either by means of piezocrystals (just as in Weber's arrangement [1], for example) or by means of the light scattering on the sound aroused by G.W. It is of great interest the utilization of substances' critical states as a detector; the large compressibility of the former affords the maximum of possible changes of their density in a definite gravitational field. They have discussed one kind of experiment in [4] (denoted here as I) in which the presence of the gravitational flow caused periodical changes of the freguency of the light scattered on the fluctuations of one of the components of the two – component solution in its critical state of stratification.

ISSN:0038-7010    

DOI:10.1080/00387017208064685

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The extremely weak fluorescence of the rare-earth ions in aqueous solutions is enhanced considerably by replacing H2O with D2O (1,2).

ISSN:0038-7010    

DOI:10.1080/00387017208064686

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor