No abstract available

[en] The rate constant for the near-resonant electronic energy transfer process NF(a ¹Δ)+Bi(⁴S/sub 3/2/) → NF(X ³Σ) +Bi(²D/sub 3/2/)+16 cm^-1 has been measured to be 1 x 10^-9 cm³ molecule^-1 sec^-1. The effective cross section (approx.200 A²) is one of the largest that has been measured for such a process, and cannot be accounted for in terms of a long-range interaction between charge distributions

[en] Capacitively coupled plasma reactive ion etching of silicon by injecting nitrogen trifluoride (NF₃) gas was conducted, and the etching process was studied with a residual gas analyzer and an optical emission spectroscopy. During the etching of silicon by the NF₃ plasma, the currents of F⁺ and SiF⁺₃ ions were obtained from the residual gas analyzer. At the same time, the line intensity of fluorine was measured using optical emission spectroscopy. The ion currents of F⁺ and SiF⁺₃ and the line intensity of fluorine were highest for etching at high pressure. With the results of this study, the general characteristics of reactive ion etching of silicon by using NF₃ plasma were confirmed. In addition, by simply changing the flow rate of NF₃, a high NF₃ flow rate was found to result in a high etch rate because of the reduced residence time.

[en] The potential energy curves and dipole moments for the low-lying electronic states of the NF molecule are found by using highly accurate multireference configuration interaction plus the Davidson correction with the AV5Z basis set. All 16 electrons are used in the correlation energy calculations, which are used to characterize the spectroscopic properties of a manifold for singlet and triplet states. X³Σ^-, a¹Δ, b¹Σ⁺, A³Π, 2³Σ^-, 2³Π, 2¹Δ, 3³Σ^-, 1³Σ⁺, and 1³Δ electronic states correlate with the two lowest dissociation channels N(⁴S_u) + F(²P_u) and N(²D_u) + F(²P_u) are investigated. Note that the b¹Σ⁺ state has two depth wells, but only one depth well was observed in the experiment. The spectroscopic parameters (R_e, ω_e, ω_eχe, D_e, B_e, and T_e) are derived, which are in excellent agreement with the available experimental data and the other theoretical values. The molecular parameters and dipole moments for the ground and excited states are also obtained. (author)

[en] The methods used to calibrate the Fly's eye detector to evaluate the energy of EAS are discussed. The energy of extensive air showers (EAS) as seen by the Fly's Eye detector are obtained from track length integrals of observed shower development curves. The energy of the parent cosmic ray primary is estimated by applying corrections to account for undetected energy in the muon, neutrino and hadronic channels. Absolute values for E depend upon the measurement of shower sizes N sub e(x). The following items are necessary to convert apparent optical brightness into intrinsic optical brightness: (1) an assessment of those factors responsible for light production by the relativistic electrons in an EAS and the transmission of light thru the atmosphere, (2) calibration of the optical detection system, and (3) a knowledge of the trajectory of the shower

[en] High resolution infrared spectra of transient species have been measured in the gas phase using tunable semiconductor diode lasers in the 9 and 11 μm regions. The spectra were recorded after a single pass of the laser either along a discharge-flow tube or through a conventional infrared sample cell. The laser spectrum of the chlorine atom at 11.3 μm has been assigned to the ²P₁sub(/)₂ <-²P₃sub(/)₂ fine structure transition and shows several resolved hyperfine features. The spectra of NF₂ arise from absorptions in the ν₁ and ν₃ fundamental bands, and many components in the sup(R)Qsub(K) branches of the ν₁ band have been assigned. Two other transient species have also been detected and tentatively identified as CF₂(ν₃) and HO₂ (ν₃). (orig.)

No abstract available

[en] This paper shows that the rf capacitive discharge in NF₃ and SiH₄ can burn in three possible modes: weak-current α-mode, strong-current γ-mode and dissociative δ-mode. This new dissociative δ-mode is characterized by a high dissociation degree of gas molecules (actually up to 100% in NF₃ and up to 70% in SiH₄), higher resistivity and a large discharge current. On increasing rf voltage first we may observe a weak-current α-mode (at low NF₃ pressure the α-mode is absent). At rather high rf voltage when a sufficiently large number of high energy electrons appear in the discharge, an intense dissociation of gas molecules via electron impact begins, and the discharge experiences a transition to the dissociative δ-mode. The dissociation products of NF₃ and SiH₄ molecules possess lower ionization potentials, and they form an easily ionized admixture to the main gas. At higher rf voltages when near-electrode sheaths are broken down, the discharge experiences a transition to the strong-current γ-mode

[en] The electron energy distribution function and the corresponding plasma parameters are studied numerically in a decaying Ar-NF₃ plasma in the presence of an external electric field. It is shown that, in this plasma, a steady-state energy distribution is established. The shape of the distribution function changes qualitatively when the electric field strength exceeds a certain threshold value. In this case, a so-called inverse distribution function forms and the electron mobility (the electron drift velocity) rapidly decreases and becomes negative. This effect is explained in terms of the specific energy dependence of the cross section for electron attachment to NF₃ molecules. The possibility of experimental observation of negative electron mobility in a decaying plasma is discussed

No abstract available