Pulsed quantum-cascade-laser spectroscopy with intermediate-size pulses: application to NH3 in the 10 μm region

摘要: Pulsed quantum-cascade-laser spectrometers are usually used to detect atmospheric gases with either the interpulse technique (short pulses, typically 5–20 ns) or intrapulse (long 500–800 ns). Each of these techniques has its drawbacks. Particularly gas absorption spectra generally distorted. We have previously developed another called intermediate-size pulses (typically 50–100 for detection using pulsed QCL spectrometers. In this paper, infrared ammonia recorded in 10 μm region presented. For NH3 at low pressure (i.e. mbar range), show typical oscillations after absorption. The Beer–Lambert law cannot explain oscillations, termed rapid-passage effect. Comparisons between experimental and calculated will be realized. This phenomenon is not satisfactory from a spectroscopic point view must higher pressures. 50 disappear could reused. paper demonstrate that gives reliable measurements detection. Moreover apparatus function (0.003 cm−1 HWHM) far lower (0.015 HWHM).