Radio-Frequency Spectrum of Metastable N2(A 3Σu+). I. Magnetic Hyperfine and Electric Quadrupole Constants

Abstract

Measurements have been made of the rf spectrum of metastable N2(A 3Σu+) by the molecular beam magnetic resonance method. Transitions obeying selection rules δF = 0, δMF = ± 1, were observed in states with quantum numbers (N, J, F) equal to (0, 1, 2), (0, 1, 1), (1, 2, 1), (1, 2, 2), (1, 2, 3), (2, 1, 1), and (2, 3, 2). The theoretical basis of this spectrum is presented in detail and used to derive hyperfine constants and the following molecular averages: Fermi contact: ∑ i′12〈δ(rai)〉Φ = (2.7 ± 0.4) × 1023cm−3, Electron–nuclear dipolar: ∑ i′12〈rai−3(3 cos2ωai − 1)〉Φ = (− 4.3 ± 0.4) × 1024cm−3, Quadrupole coupling: e2q0Q / h = − 1.8 ± 1.0 MHz (primes indicate that the summations are to be carried out over only the unpaired electrons).