Measurement of the strengths of 1 ← 0 and 3 ← 0 transitions of HI using frequency modulation spectroscopy

Spectral line parameters in the (3←0) overtone band of the HI molecule and line-mixing in the band head

“…For instance, the above ±12% variation of l 40 changes C 30 by ±3 · 10 À4 , while for D 30 the change is in the range from À1.8 · 10 À5 to +4.8 · 10 À6 . This property is also revealed by a diversity of the published estimates for D 30 : À1.4 · 10 À5 [6], À2.7 · 10 À3 [4], and +2.3 · 10 À5 [15]. Obviously no accurate theoretical values for the D t0 (t P 3) coefficients can be obtained from the currently available set of the dipole parameters for HI.…”

“…It follows that the meaningful values of experimental dipole matrix elements for the m P 11 transitions can be obtained only at the gas pressures low enough to preclude collision-induced line overlap. We note that the results of Riris et al [4] for the higher-J lines plotted in Fig. 1 may probably also appear distorted by line-mixing.…”

“…Meyer et al [3] made low-resolution measurements of the |m| 6 9 lines, and Riris et al [4] tabulated intensities for the R 3 (2) À R 3 (5) and R 3 (16) À R 3 (18) lines measured by a frequency modulation diode laser spectroscopic technique. Several empirical dipole moment functions were proposed based on these and other published experimental data on different vibrational transitions of HI [2,[4][5][6].…”

Spectral line parameters in the (2←0) overtone band and the dipole moment function of the HI molecule

“…The absolute strengths for the P 2 ð9Þ to R 2 ð9Þ lines were later measured by Meyer et al [3]. Other available electric dipole parameters for the HI molecule relevant in the context of the present work comprise the vibrational ground-state dipole moment [4] and the line intensities in the (3 0) [3,5], (4 0), and (5 0) [6] higher-order overtone bands. Several ab initio dipole moment functions for HI have also been calculated at different levels of sophistication during last decades [7][8][9][10][11][12].…”

Two-tone frequency-modulation spectroscopy for quantitative measurements of gaseous species: theoretical, numerical, and experimental investigation of line shapes

“…[1][2][3][4][5][6][7][8] Applying TTFMS for quantitative measurements over a wide range of concentrations, temperatures, or pressures requires information about the line parameters and an adequate theory of the heterodyne detected signal. The line parameter data can be found with varying accuracy in the literature and in databases.…”