Branching ratio measurements for the NO γ bands excited by energy transfer from metastable nitrogen molecules show that the electronic transition moment for the NO(A 2Σ+–X 2Π) transition varies by about 40% over the r‐centroid range of 1.13–0.97 A. Combining this transition‐moment variation with radiative lifetime measurements provides a complete set of Einstein coefficients for NO(A–X) transitions from v’=0–2.

Einstein coefficients and transition moment variation for the NO(A 2Σ+–X 2Π) transition

The potential curves for the X 2Π and A 2Σ+ states of NO have been determined using large Gaussian basis sets and accounting for electron correlation with the MCPF and CASSCF/multireference CI methods. The A 2Σ–X2Π electronic transition moment (γ system) is found to increase monotonically with decreasing internuclear distance. It differs significantly from the functional form deduced empirically from either branching ratio or lifetime measurements. The increase in the moment as r decreases is correlated with the increasing degree of diffuse character in the X 2Π state. Inclusion of 2s correlation is found to have a relatively small effect on the functional form of the moment once the valence correlation is accurately determined. However, the NO γ system transition moment is found to be sensitive to the choice of the molecular orbital basis. The X 2Π and A 2Σ+ dipole moment functions are studied to provide an additional assessment of the quality of the wave functions. The X 2Π vibrationally averaged dipole...

Theoretical study of the NO γ system

High resolution dipole (e, e) spectroscopy has been used to measure absolute optical oscillator strengths for the photoabsorption of nitric oxide in the valence shell region over the equivalent photon energy range 5–30 eV. Absolute optical oscillator strengths for the vibronic transitions of the γ(A 2Σ+-X 2Π), β(B 2Π-X 2Π), δ(C 2Π-X 2Π) and ϵ (D 2Σ+-X 2Π) systems have been obtained. The present results are compared with previously published experimental data and theoretical calculations.

Absolute optical oscillator strengths for the photoabsorption of nitric oxide (5–30 eV) at high resolution

Absorption oscillator strengths for the γ(A 2 Σ + -X 2 Π). δ(C 2 Π-X 2 Π), and ∈(D 2 Σ + -X 2 Π) bands of NO, which are relevant to the study of atmospheric processes are reported. We have calculated both electronic and vibronictransition probabilities with the molecular-adapted quantum defect orbital (MQDO) method, which has proved, in previous applications, to be an adequate theoretical tool in the context of Rydberg spectra. The results appear to be in good accord with the available experimental values and, with some exceptions, conform fairly well with theoretical data derived from rather more sophisticated methods.

Intensities of vibronic transitions for the main bands observed in the electronic spectrum of atmospherically relevant nitric oxide

An optically pumped ultraviolet laser on SO (B 3Σ--X 3Σ-)

Lasing action on the (0,1) and (0,2) γ bands of NO at 237 and 248 nm, respectively, has been obtained by longitudinal pumping of 0.5 Torr of NO on the (0,0) γ‐band transition at 227 nm. Typical output pulse energies were 13 μJ at an intrinsic energy conversion efficiency of approximately 15%.

Michael D. Burrows

Papers

Optically pumped NO (A 2Σ+→X 2π) ultraviolet laser