Phosphorescence excitation spectra of benzaldehyde and its derivatives have been observed in supersonic jets. We have also observed the dispersed phosphorescence spectrum of benzaldehyde and found the intramolecular vibrational redistribution (IVR) in the triplet manifold. The fast radiationless transitions in aromatic carbonyl molecules are induced by the interactions among four electronic states, that is, Sll(nn*), 3(nn*), 3(nn*), and the SO ground state. Particularly, the change in the vibronic coupling between the 3(nn*) and 3(nn*) states is important for the substitution effect. In the halogen and methyl-substituted benzaldehydes, the vibronic bands were found to be remarkably weakened. It is considered to be due to the dilution of the 3(nn*) levels by the nonphosphorescent 3(nn*) levels and the coupling with the ground state. In 4-pyridinecarboxaldehyde, however, the intersystem crossing (ISC) is relatively slow because the 3(nn*) energy is higher and the coupling with the Sll(nn*) state is not strong compared with that of benzaldehyde.

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The effects of the “electron shading” charge build-up at the bottom of holes are investigated using fluorocarbon gas plasma. The etch rates of the electrically conductive films such as phosphorus-doped polysilicon at the bottom of the holes change depending on whether the films are patterned or not. This is caused by the decrease of the low-energy ions which reach the bottom of the holes due to positive charging of the underlying layers. Furthermore, the potential at the bottom of the contact holes is investigated using metal-nitride-oxide-silicon (MNOS) capacitors. The positive charging due to the electron shading effect is measured. In order to reduce the electron shading charge build-up, the pulse-modulated plasma is investigated. The selectivity to the underlying layer increases upon using pulse-modulated plasma.

Phosphorescence and fluorescence excitation spectra of oxalyl chloride (COCl) 2 have been observed in a supersonic jet. Strong phosphorescence was observed for excitation of the 0 0 0 band of the T 1 3 A u (nπ*) r S 0 transition. From a vibrational analysis, it is shown that the molecule has C 2h symmetry in the T 1 excited state as well as in the S 0 ground state. Small splittings due to 35 Cl and 37 Cl isotopes were found in several vibronic bands. For the excitation of the S 1 0 0 0 band, phosphorescence with a short lifetime was observed, indicating fast intersystem crossing in the origin level. In the higher energy region, we could not observe phosphorescence but only weak fluorescence. It suggests existence of active nonradiative processes such as internal conversion and predissociation in the vibrationally excited levels of the S 1 state. A single-vibronic-level (SVL) dispersed phosphorescence spectrum has also been observed for the excitation of the T 1 CdO stretching band. The spectrum was dominated by bands at the same wavelengths as those for the 0 0 0 excitation. This clearly shows that intramolecular vibrational redistribution (IVR) takes place within the long triplet lifetime. Although oxalyl chloride is assumed to be a "small molecule", the radiationless transitions have been found to be efficient in both the T 1 and S 1 states.