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 Å/mm at the exit slit. The resolution achieved was energy limited at 0.046 cm<sup>-1</sup> and the precision of frequency measurement was 0.007cm<sup>-1</sup>. The 0-0 band of the <i>B</i>′<sup>3</sup>Σ<sup>-</sup><sub><i>u</i></sub>→ <i>B</i><sup>3</sup>II<sub><i>g</i></sub> 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 region are from the 0-0 <i>B</i>′ → <i>B</i> transition, with only a small 1 <i>PG</i> emission toward the red end of the band.
© 1978 Optical Society of AmericaPDF Article