Ground State N2 Molecules Research Articles

Quenching of 4He and 3He excited states by collisions with N2

A time-resolved spectroscopy method combined with pulse electron excitation are used for the experimental investigation of the quenching process of He excited states by collisions with nitrogen molecules in a He–Ne–N2 mixture at low pressure. The rate constants for quenching 4He(21S), 4He(21P), 3He(21S) and 3He(21P) states by collisions with ground state N2 molecules at Tg=600K are: k=(2.66±0.09)×10-10 and k=(1.89±0.28)×10-9cm3s-1 for 4He(21S) and 4He(21P), respectively, and k=(2.81±0.07)×10-10 and k=(3.21±0.58)×10-9cm3s-1 for 3He(21S) and 3He(21P), respectively.

The N4 molecule and the N3 + ion

The possibility of the nitrogen molecule forming a stable dimer is investigated. Through ab initio calculations in an extended contracted-gaussian basis, it is demonstrated that N4 in tetrahedral geometry and N3 + in D 3h geometry are local minimum points on their respective internuclear potential energy surfaces. The N4 molecule is considerably higher in energy than two ground-state N2 molecules and some study of the barrier for N4 decomposition has been made. The bond lengths and force constants for the two systems are shown to be similar to their hydrocarbon counterparts, C4H4 and C3H3 +, tetrahedrane and cyclopropenyl cation. Other related systems are discussed as well.

Elektronennachlieferung in Niederdruckentladungen durch metastabile Stickstoffmoleküle und deren Stoßlöschung durch Fremdgase

Oscilloscopic studies of pre-breakdown discharge currents in pure nitrogen and mixtures of nitrogen with other gases show that metastable N2 molecules influence the discharge by releasing secondary electrons when they collide with the electrodes. By this slow process an after current is produced, which lasts a time of milliseconds. It was found that the diffusion coefficient of the metastable N2 molecule is 167 cm2 s−1 ±15% at 1 Torr and 20°C, its radiative life time is larger than 40 ms, and its cross section for deexciting collisions with ground state N2 molecules is smaller than 7 · 10−22 cm2. There is strong evidence that the metastables are in theA3Σu+ state. From measurements in gas mixtures cross sections for deexciting collisions with other molecules are derived. The results are for O2 1.9 · 10−17 cm2, for CO 1.5 · 10−17 cm2, for H2 2.5 · 10−20 cm2, and for CO2 smaller than 5 · 10−20 cm2.