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"Experimental determination of the self-, N2- and O2-broadening parameters of the pure rotational transition J = 6(1,6) - 5(2,3) of H2O at 22.2 GHz".
No full textPressure-broadening of water lines in the THz frequency region: Improvements and confirmations for spectroscopic databases. Part I
No full textThe self-, nitrogen- and oxygen-broadening of the J = 7(2,5) - 8(1,8) (1.147 THz), 8(5,4) - 7(6,1) (1.168 THz), 7(4,4) - 6(5,1) (1.173 THz), 8(5,3) - 7(6,2) (1.191 THz), and 6(3,3) - 5(4,2) (1.542 THz)
rotational transitions of water vapor have been experimentally and theoretically investigated in the present work, showing that the corresponding HITRAN selfbroadening parameters are affected by large errors. Indeed, simple semiclassical calculations performed for more than 1500 rotational water lines with wavenumber below 1000 cm-1 allow us to improve the self-broadening values reported in the HITRAN database when obtained by assuming a J dependence. On the other hand, our measurements and calculations confirm the values reported in the HITRAN database for
air-broadening and shift, which are based on semiclassical computations as well. On the whole, the present investigation provides new experimental as well as theoretically improved values for self-broadening parameters of rotational lines in the THz frequency region
Pressure-broadening in the THz frequency region: the 1.113 THz line of water
No full textIt is well established that water plays a fundamental role in various atmospheric phenomena and that the accuracy of its collisional broadening parameters has a crucial influence on reduction of remote sensing data. Nevertheless, in this field the experimental data are still scarce and consequently the estimates reported in spectroscopic databases are not always reliable and/or accurate. In the view of filling this gap, the self-, N2- and O2-broadening parameters of the J = 1_11 - 0_0,0 rotational transition of water (1.113 THz) have been determined at room temperature. The experimental investigation has also been supported by theoretical calculations
Experimental and theoretical investigation on pressure-broadening and pressure-shifting of the 22.2 GHz line of Water
No full textPressure-broadening of the 22.2 GHz line of Water: basic results for Remote Sensing of the Atmosphere
No full textFor atmospheric purposes, the self- and N2-broadening parameters of the J = 6_{1,6} - 5_{2,3} (22.2 GHz) rotational transition of water has been investigated in the temperature range 296-338 K. This investigation should be considered of particular interest in
monitoring the Earth's atmosphere because water is a fundamental component and it is well established that the accuracy of collisional
broadening parameters has a crucial influence on reduction of remote sensing data. Therefore, a particular effort has been made in order to reduce instrumental as well as systematic errors. Experimental determinations have also been supported by theoretical calculations
Experimental and Theoretical Study of the Broadening and Shifting of N2H+ Rotational Lines by Helium
No full textPressure broadening and pressure shift of N2H+ rotational lines perturbed by collisions with He are studied for the first time using experiment and theory. Results are reported from measurements at 88 K for the rotational transitions equation image, equation image, equation image and equation image with frequencies ranging from 0.28 to 0.56 THz. The agreement between experiment and theoretical data derived from close coupling calculations confirms the reliability of a theoretical framework used for state-to-state transition rates of interest in the interpretation of spectroscopic data from interstellar molecular clouds. The influence of hyperfine effects on shifts and widths of the rotational lines is discussed in detail. Although in principle possible, experiment and theoretical considerations lead to the conclusion that hyperfine effects only play a minor role
An acoustic approach to millimeter wave linewidth spectroscopy
No full textOn décrit un nouvel appareil expérimental pour la mesure de l'élargissement par collision des raies rotationnelles dans la région des ondes millimétriques. La cellule qui contient le gaz est un détecteur acoustique avec une grande sensibilité à basse pression. On compare les coefficients d'élargissement mesurés et théoriques pour le CH3CN et le CH813Br.We describe a novel experimental apparatus to measure the collision broadening of rotational lines in the millimeter-wave region. The sample cell is a small acoustic detector featuring high sensitivity at low pressure. We measured the broadening coefficients for CH3CN and CH813Br and we compared them with the theoretically estimated linewidths
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