X. Thomas

Line intensities of the: ν3, 4ν2, ν1+ν3, 3ν1 and 2ν1+2ν2 bands of 16O12C32S molecule

Abstract The line intensities of the ν3 band of OCS used for atmospheric retrievals, has been measured. The spectra have been recorded with the Reims Fourier transform spectrometer. Other bands of OCS 4ν 2 , ν 1 +ν 3 , 3ν 1 and 2ν1+2ν2 were recorded to obtain the line intensities. The results are compared to usual databanks (HITRAN or GEISA). From the measured line intensities, it has been possible to estimate the square of the vibrational dipole moment matrix element ( in debye 2 ) , equal to 0.1313 1 , 7.840 9 ×10 −4 , 1.158 1 ×10 −3 , 1.218 3 ×10 −5 , 1.192 3 ×10 −5 , respectively, for ν 3 , 4ν 2 , ν 1 +ν 3 , 3ν 1 and 2ν1+2ν2.

Broadening parameters of NO2 lines in the 3.4 μm spectral region

Abstract Fourier transform spectra have been recorded to measure self-, N 2 -, and O 2 -broadening coefficients of NO 2 lines in the v 1 + v 3 band. For the studied set of transitions, a slight rotational dependence of the broadening coefficients exists versus N ″, the rotational quantum number of the lower level of the transition, whereas no significant dependence is observed versus K a ″. An empirical relation, allowing one to calculate approximate values of the air-broadening coefficients γ air 0 , at 296 K, for lines observable in atmospheric spectra recorded from the ground, is proposed: γ air 0 = 84.1 − 0.753 N ″ + 0.0059 N ″ 2 , in 10 −3 cm −1 ·atm −1 , with an uncertainty of about ± 10% when N ″ and K a ″ are smaller than about 40 and 10, respectively. For typical lines used for atmospheric applications, the single value reported in the HITRAN database for all lines of all bands of NO 2 can differ by more than 20% from the measured ones.

Intensities of N2O measurements in the 4 and 3 μm region using fourier transform spectrometer

Abstract Absolute intensities of transitions of four bands of N 2 O in very good self consistency are obtained and compared with recent literature data. Intensities from the transition dipole moment are also calculated. To obtain these results, special care is taken for all experimental set-up and to obtain a true zero transmittance for the Fourier Transform Spectrometer of Reims, working in stepping mode. Three types of improvements are performed leading to a zero level better than 0.5% and then resulting in an absolute accuracy better than 2% in the intensity measurements for N 2 O.

Tunable diode laser spectrometer apparatus function

Abstract Lead-salt diode lasers (TDL) are extensively used in experiments involving absorption line intensity and absorption linewidth measurements. In these experiments, the finite TDL linewidth poses a problem and it is necessary to know precisely the TDL lineshapes and linewidths. For this purpose, three methods are used: records of spectra at low pressure, etalon fringes analysis and heterodyne measurements.