Search results for "INVERSE RAMAN-SPECTROSCOPY"
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Femtosecond polarization spectroscopy in molecular gas mixtures: Macroscopic interference and concentration measurements
2000
0021-9606; Raman-induced polarization spectroscopy (RIPS) experiments combined with homodyne detection have been conducted with a femtosecond laser at room temperature and low pressure (p < 2 atm) in CO2-N2 mixtures as well as in air (O2-N2 mixtures). Each molecule of the mixture produces its own time-dependent signal, measured as a series of recurring transients. Macroscopic interference is observed when transients of both molecules overlap in the time domain. This interference leads to a large modification of the signal, which is well reproduced by calculations. The total signal recorded in CO2-N2 or O2-N2 mixtures of known concentration is analyzed in order to measure the polarizability …
Application of time-resolved spectroscopy to concentration measurements in gas mixtures
2001
1296-2147; Concentration measurements using femtosecond Raman Induced Polarization Spectroscopy (RIPS) are performed in binary gas mixtures CO2-N2 and CO2-N2O at room temperature. The principle of these measurements is based on the nonlinear rotational time response of each molecular component of the mixture, The general form of this molecular response is a series of periodic transients with a period related to the rotational constant Be The relative strength of the individual responses allows an accurate determination of the concentration. Two techniques are presented using either two pulses (one pump and one probe) or three pulses (two pumps and one probe). (C) 2001 Academie des sciences/…