AbstractsFranck-Condon factors are presented for the normal and stable isotope-labelled N, , 0, , N O and CO molecules for transitions to the observed ionized states by using the Rydberg-Klein-Rees (RKR) potential energy curves of the various electronic states involved. It has been observed that for some transitions, the Franck-Condon factors based on the RKR potential energy curves differ appreciably from those based on the Morse potential function. The effect of isotopic substitution OR the transition probabilities is also quite significant in a number of cases.O n a calcult des facteurs de Franck-Condon pour les molCcules N, , 0, , NO et CO pour les transitions aux Ctats ionisCs observes. Les calculs ont Ct C basts sur les courbes de potentiel de Rydberg-Klein-Rees (RKR) des Ctats Clectroniques en question. On a observe que pour certaines transitions, les facteurs de Franck-Condon basts sur les courbes de potentiel RKR diff6rent d'une fason apprtciable de ceux obtenus de la fonction de potentiel de Morse. L'effet d'une substitution isotopique sur les probabilites de transition est aussi significatif dans plusieurs cas.Franck-Condon-Faktoren wurdenfur die Molekule N, , 0, ,KO und COfur Ubergange zu den beobachteten ionisierten Zustanden mit den Rydberg-Klein-Rees (RKR) Potentialkurven der entsprechenden elektronischen Zustande berechnet. Es wurde bemerkt dass fur gewisse Ubergange die Franck-Condon-Faktoren der RKR Potentialkurven merkbar von den der Morse-Potentialfunktion abweichen. Der effekt isotopischer Substitution auf den Ubergangswahrscheinlichkeiten ist auch in vielen Fallen ganz bedeutsam.
9263assignment of this species is far from conclusive, the spectrum can be interpreted in terms of two different 31P hyperfine interactions. A likely candidate for this species is an intermediate of the conversion of a localized center into a PLP u* dimer radical cation.
Experimental SectionBis(dipheny1phosphine)s were obtained from Aldrich and were used as received. Dichloromethane was dried by passing over a basic alumina column.X-irradiation and ESR. Solutions of bis(diphenylphosphin0) derivatives in CH2CI2 ( 1 M) were degased by three consecutive freeze-pump-thaw cycles and subsequently frozen at 77 K in liquid nitrogen. The samples were X-irradiated at 77 K for 4 h using a Cu source, operating at 40 kV and 20 mA. X-band ESR spectra were recorded on a Bruker ER200D spectrometer, interfaced with a Bruker Aspect 3000 computer for digital storage. Typical spectra were recorded with 4K data points and a sweep width of 187.5 mT. Microwave power was 2 mW in most experiments. Temperature was controlled with the aid of a Bruker ER 4111 variable-temperature unit between 95 and 170 K. Hyperfine couplings and g values were determined from the spectra by using second-order corrections.20 (20) Weltner, W. Magnetic Atoms and Molecules; Scientific and Academic Editions: New York, 1983.NMR Conformation Analysis. N M R spectra were recorded on a Bruker AM400 spectrometer, at frequencies of 400.1, 162.0, and 100.6 M H z for 'H, 31P, and I3C, respectively. In all N M R experiments we used CD2C12 as solvent.
studies is that we may justifiably include such effects in future ligand-field analyses when the chemistry demands, even though such inclusion may not be analytically supportable by the given data and circumstances. After all, the neglect of the ß parameter in the presence of nearby lone pairs or of bent bonds constitutes an assumption in itself. Far better, surely, to guess-though not refine, perhaps-a nonzero value for it by informed extrapolation from the present studies and so improve estimates of the remaining CLF parameters that are optimized. Of course, we do not expect to find CLF values for misdirected valence to be any more transferable between systems than are diagonal ex values.Acknowledgment. R.J.D. acknowledges the award of a Commonwealth Scholarship and support of the British Council.
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