Threshold electron impact spectrum of N2O

Using a high-resolution electron impact monochromator combined with a penetrating-field analyser for efficient detection of electrons of nearly zero energy, the first high-resolution electron impact spectrum of N 2 O was obtained. The threshold spectrum is presented over a wide energy range for 1.5 to 17.5 eV. Decay of a low-energy shape resonance into the vibrationally excited ground state was observed. Several new optically forbidden and previously unobserved Rydberg states were detected.