Intensities, broadening and narrowing parameters in the ν 3 band of methane

Highly Sensitive, Calibration-Free WM-DAS Method for Recovering Absorbance—Part II: Experimental Analysis

“…In the spectral line parameters measurement, to further increase the measurement accuracy, more and more attention is paid to some weak mechanisms, especially the line narrowing effect. The pronounced gull-wing signature in the best-fit Voigt profile residual and its disappearance in more advanced GP, RP, or SDVP profile fit suggest the non-negligible collisional narrowing effect [1,3,19,20]. In addition, as reported by David A.…”

“…Through years of development, tunable diode laser absorption spectroscopy (TDLAS) has become one of the most important approaches in gas monitoring and has succeeded in various fields, including spectral line parameter measurements [1][2][3][4], and the diagnostic of combustion [5][6][7][8][9] and plasma [10][11][12]. Particularly, the 2f /1f method introduced by Hanson et al [13][14][15] that overcomes the complicated calibration issue has further promoted the TDLAS technique toward practical applications.…”

H2-induced pressure broadening and pressure shift in the P-branch of the ν3 band of CH4 from 300 to 655 K

“…In the following, we will discuss the comparison of our results with the most relevant literature data. Figure 7 represents the comparison of our results with the literature data [35,65,66,72,73] for the CH 4 @[H 2 ] ν 3 band. Note that most of the previous studies have been for the Q branch [35,72] and employed Rautian line profiles; while there are a few measurements on the P branch [65,73], none employ H 2 as a broadener.…”

“…In general our n γ coefficients (@[H 2 ]) is smaller than both @[Air]-broadening and @[N 2 ]-broadening 5. Figure 9 represents the effect of various broadeners (i.e., self or CH 4 , N 2 , and He) on γ L for different T d symmetry species [35,43,65,66,72,73]. In general γ L (Self) > γ L (H 2 ) γ L (N 2 ) > γ L (He).…”

Recent advances in collisional effects on spectra of molecular gases and their practical consequences

“…This molecule might be present at the parts-per-billion level and detecting it requires highly sensitive observations at high spectral resolution together with very accurate spectroscopic parameters. This has motivated several studies to derive CO 2 -broadening line widths and LM effects in CH 4 to prepare for upcoming observations (eg [453,454,501]). Despite the low surface pressure on Mars (600 Pa on average), LM effects are visible in CH 4 spectra at the spectral resolution of the NOMAD spectrometer (0.1 cm -1 ) onboard ExoMars Trace Gas Orbiter [453] and they will be taken into account.…”