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High-resolution spectra corresponding to the rotational and the ν2–ν2 bands of the two most abundant isotopic species of ozone with one heavy 18O oxygen atom were recorded using SOLEIL synchrotron radiation source in the range 30–200 cm−1. Additionally, the ν2 vibrational-rotational bands were recorded between 550 and 880 cm−1 using a classical glowbar source that made it possible to extend and refine information compared to published data on the observed transitions of these bands. The analyses of recorded spectra permitted us to deduce experimental set of energy levels for the ground (000) and the first bending (010) vibrational states, which significantly exceeds literature data in terms of rotational quantum numbers. For both isotopic species, the weighted fits of all experimental line positions were carried out including previously published microwave data. As a result of this work, the improved values of rotational and centrifugal distortion parameters for the states (000) and (010) were obtained that permitted modelling the experimental line positions with a weighted standard deviation of 1.284 (2235 transitions) and 0.908 (4597 transitions), respectively, for 16O16O18O, and 1.168 (824 transitions) and 1.724 (2381 transitions) for 16O18O16O. [ABSTRACT FROM AUTHOR]

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

The same quantum cascade laser spectrometer working around 9 μm was used in both continuous-wave and pulsed modes to compare their own characteristics. The laser emitting in continuous-wave mode was mainly used to study some spectroscopic parameters of SO2 ro-vibrational lines. This work demonstrates the necessity to use new calculations previously developed instead of conventional databases such as HITRAN. In addition, the same laser emitting in pulsed mode with long pulses (600 to 900 ns) was used to record SO2 spectra with the intrapulse technique. This work permits us to make comparisons about those two modes of emission for the development of future spectrometers. [ABSTRACT FROM AUTHOR]