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Single vibronic level dispersed fluorescence spectra of jet-cooled HGeBr, DGeBr, HGeI, and DGeI have been obtained by laser excitation of selected bands of the à 1A″-X 1A′ electronic transition. The measured ground state vibrational intervals were assigned and fitted to anharmonicity expressions, which allowed the harmonic frequencies to be determined for both isotopomers. In some cases, lack of a suitable range of emission data necessitated that some of the anharmonicity constants and vibrational frequencies be estimated from those of HGeCl/DGeCl and the corresponding silylenes (HSiX). Harmonic force fields were obtained for both molecules, although only four of the six force constants could be determined. The ground state effective rotational constants and force field data were combined to calculate average (rz) and approximate equilibrium (rez) structures. For HGeBr rez(GeH)=1.593(9) Å, rez(GeBr)=2.325(21) Å, and the bond angle was fixed at our CCSD(T)/aug-cc-pVTZ ab initio value of 93.6°. For HGeI we obtained rez(GeH)=1.589(1) Å, rez(GeI)=2.525(5) Å, and bond angle=93.2°. Franck-Condon simulations of the emission spectra using ab initio Cartesian displacement coordinates reproduce the observed intensity distributions satisfactorily. The trends in structural parameters in the halogermylenes and halosilylenes can be readily understood based on the electronegativity of the halogen substituent. [ABSTRACT FROM AUTHOR]

Single vibronic level dispersed fluorescence spectra of jet-cooled HGeCl and DGeCl have been recorded by laser excitation of selected bands of the à 1A″–X 1A′ electronic transition. Twenty-six ground state vibrational levels of HGeCl and 42 of DGeCl were measured, assigned, and fitted to standard anharmonicity expressions, which allowed all the harmonic frequencies to be determined for both isotopomers. A normal coordinate least squares analysis obtained by fitting the harmonic frequencies yielded reliable values for five of the six force constants. The ground state effective rotational constants and force field data were combined to calculate average (rz) and approximate equilibrium (rez) structures, with rez(GeH)=1.586(1) Å, rez(GeCl)=2.171(2) Å, and the bond angle fixed at our CCSD(T)/aug-cc-pVTZ ab initio value of 93.9°. Comparisons show that the derived bond lengths are consistent with those of the appropriate diatomic molecules in their ground electronic states and the bond angle is similar to that of germylene (GeH2). A Franck-Condon simulation of the vibrational intensities in the 000 band emission spectrum of HGeCl using ab initio force field data shows good agreement with experiment, lending credence to the vibrational analysis of the observed spectra. [ABSTRACT FROM AUTHOR]

Research was conducted to examine the white light electroluminescence from a fluorescent C60 adduct-single layer organic light-emitting diode (LED). A C60 adduct, T(sub h)-hexapyrrolidine (THP) was utilized as a chromophore in the fabrication of a white light organic LED due to its photophysical properties. Results demonstrate the successful fabrication of a single layer, white light, organic LED by blending the fluorescent T(sub)-hexapyrrolidine C60 adduct with PVK and BND which is the first known example of electroluminescence from a C60 derivative.