Magnetic Faraday modulation spectroscopy of the 1–0 band of 14NO and 15NO

Magnetic rotation spectroscopy signals of the nitric oxide (NO) fundamental band near 5 μm have been observed and compared with calculated signals. This spectroscopic approach exploits magnetic field modulation in the Faraday configuration for very sensitive detection of NO. Line shapes and strengths of the Faraday signals depend on molecular parameters, like J and Ω quantum numbers of the transitions involved, and on experimental parameters, like pressure of the gas sample and applied external magnetic field strength. In this study we implemented a software model which provides a simulation of the complete v=1–0 Faraday spectrum of NO. The algorithm considers the magnetic field modulation, the collisional and Doppler broadening of the line shapes, and the line intensities of 14NO and 15NO fundamental band lines. Optimum values for pressure and magnetic field modulation for maximum sensitivity are given. Suitable spectral windows for simultaneous detection of 14NO and 15NO are discussed. Experimental data were obtained in the wavenumber region from 1840 to 1900 cm−1 by means of a CO sideband laser and a quantum cascade laser. Comparison between calculated and observed signals shows excellent agreement.