New Method of Linewidth Measurement and Its Application in the Analysis of Laser Magnetic Resonance Spectra of NO₂

A new indirect method of linewidth measurement was proposed, by which the linewidths and pressure broadening coefficients of spectral lines can be derived from the dependence of the peak-to-peak amplitudes of the first derivative curve of the absorption lines on the pressures. By the application of the method in the analysis of the laser magnetic resonance spectra of v₃ band of NO₂, the foreign gas pressure broadening coefficients γ_{NO2-N2,O2,He,air}⁰ were determined to be 2.7 ± 0.1, 1.9 ± 0.2, 1.1 ± 0.2, 2.5 ± 0.1 MHz/Torr at 287K respectively. The comparable results are in agreement with those of some other papers. The obtaining of the linewidth parameters is of considerable importance to air pollution monitoring. The Method is very convenient and available. It has higher sensitivity and less disturbance of distortion and overlap of line wings. It can be further used in some other spectroscopic techniques such as microwave spectroscopy, ESR etc, to study pressure broadening of spectral lines and its temperature dependence, and the component and density of the sample gas.