Absorption spectroscopy of ammonia between 6526 and 6538 cm−1

The spectral measurements of ammonia absorption lines from 6526 to 6538 cm−1 have been performed at room temperature by using fiber-coupled distributed feedback (DFB) diode laser operating at 1.531 μm. As many as 152 lines of ammonia and its line intensities, self-broadening and air-broadening coefficients were obtained, which include many weak lines not previously reported. The 20 strongest lines were obtained using the traditional direct absorption spectroscopy technology with a 30 cm single-path cell and the other 132 lines were acquired using a compact system based on off-axis integrated-cavity output spectroscopy (OA-ICOS) with an effective optical path of 36.62 m.