High-resolution electronic emission spectrum of molecular nitrogen at 15300 Å

Abstract

The 5 m Jarrell-Ash Czerny-Turner spectrograph at the Institute for Molecular Physics has been adapted to spectrometric operation in the 1–2 μm wavelength region. A lead screw assembly with a stepping motor drive has been installed to translate an exit slit that is focused onto a cooled intrinsic germanium detector. The exceptional sensitivity of this detection system has produced good signal-to-noise ratios in the third order of a 300 line/mm echelle grating which yields a reciprocal dispersion of 1.44 A/mm at the exit slit. The resolution achieved was energy limited at 0.046 cm−1 and the precision of frequency measurement was 0.007 cm−1. The 0-0 band of the B′ Σ3u-→B Π3g system of molecular nitrogen was the subject of the investigation. Although this system is known as the infrared afterglow system, the band emits strongly in a dc glow discharge and it has been possible to resolve nearly 1000 lines in the band. The preponderance of the lines in the region are from the 0-0 B′ → B transition, with only a small 1 PG emission toward the red end of the band.