Pressure broadening coefficients of ν5 fundamental band lines of CH3I at 7μm measured by diode laser absorption spectroscopy

Line intensities for the ν6 and 2ν3 bands of methyl iodide (12CH3I)

“…For the present linelist, we decided to account for the hyperfine structure provided it leads to a Hyp hyperfine shift larger (in absolute value) than a pre-defined Hyper Limit threshold limit of 0.002 cm -1 . This lower limit more or less corresponds to the observed width of the lines in the experimental spectra studied in this work, involving the combined contributions from the Doppler width [ D (half width at half maximum) ~ 0.0005 cm -1 at T = 296 K in the studied spectral region], from pressure broadening [32] and from the experimental line shape of the FTS.…”

Methanogenic activity tests by Infrared Tunable Diode Laser Absorption Spectroscopy

“…It is well known that TDLAS is pressure-sensitive and the scientific background of such sensitivity has been well established (Hoffman and Davies, 2008). In order to determine the impact of pressure on MA-TDLAS method proposed here, different methane/air mixture were measured at several total pressures and with different CH 4 partial pressures.…”

Pressure broadening coefficients of transitions in the ν5 band of methyl bromide from fitting to Voigt and Galatry line profiles

“…Pressure broadening measurements were carried out following the procedure described in the earlier study on methyl iodide [20]. The available diode laser spectral coverage permitted 125 lines from five Q branches to be measured along with 49 P and R branch lines.…”

“…In the earlier work [20] it was found that Voigt and Galatry fits of lines recorded as first derivatives using source modulation were more accurate than fits of absorption line recordings. Hence, in this work, all the lines were recorded in first derivative mode and subsequently numerically integrated to retrieve the line profiles.…”

“…Measurements were made using the three channel diode laser spectrometer described in an earlier study of pressure broadening of methyl iodide [20]. Methyl bromide, nitrogen and oxygen (BOC) had stated purities of 99.5%, 99.998% and 99.985%, respectively, and were used as supplied.…”