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Effetti termici nell`assorbimento multifotonico infrarosso in fasci molecolari di SF6 e CF3Br
No full textOptimization and Characterization of a superconducting bolometer for molecular beam detection
No full textMeasurement of Multiphoton I.R. Absorption of SF6 molecules by means of the Laser-bolometric Technique
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Study of collisionless infrared multiple-photon absorption of SF6 in a variable temperature molecular beam.
No full textStudio del processo di eccitazione multifotonica infrarossa di un fascio molecolare di SF6
No full textInfrared multiple-photon excitation of sulfur hexafluoride in a molecular beam
No full textThe infrared multiple photon excitation of SFg in a supersonic molecular beam has been investigated by means of the laser-bolometric technique. In this experiment molecules are irradiated below dissociation threshold in a true collisionless regime. The absorbed energy is detected by means of a fast superconducting bolometer. The molecular beam is obtained by expanding pure SF6 and SF6 seeded in helium or argon at different pressures. The multiple photon excitation spectra are very sensitive to the molecular beam conditions. Spectra become narrower as the pressure is increased. This effect has been attributed mainly to the rotational cooling which occurs during beam formation
Resonant photoacoustic simultaneous detection of methane and ethylene by means of a 1.63 um diode laser
No full textA compact multi-component trace-gas detector based on the resonant photoacoustic technique and a NIR external cavity diode laser has been developed. It has been characterized using a mixture of ethylene and methane diluted in ambient air. A spectroscopic investigation of combination bands and overtones between 5900 and 6250 cm-1, obtained with an IR pulsed laser photoacoustic spectrometer, allowed us to find a wavelength region where the 2ν3 overtone of CH4 and the ν5+ν9 combination band of C2H4 show uncongested rotational lines. Using a single-mode scan of the diode laser in this region, around 6150 cm-1, the sensitivity for the simultaneous detection of ethylene and methane is 8 ppm/mW and 40 ppm/mW respectively. Factors affecting the sensitivity and selectivity of the detection system and possible improvements suitable to reach the sub-ppm detection limit are discussed
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