Infrared band intensities of formaldehyde and formaldehyde-d2

Abstract

The infrared band intensities of formaldehyde and formaldehyde-d, have been measured in the gas phase using an Ff-IR spectrometer. The effect of the polymerization of the sample molecule was minimized to measure the correct intensities. When the bands overlapped each other, their individual intensities have been determined by a band simulation calculation taking account of the Coriolis interactions. The signs of the dipole moment derivatives (iJp/iJQ;) have completely been determined by the least-squares method, and the results were compared with those obtained by the molecular orbital calculation (CNDO/2) and by the analyses of the Coriolis interactions. The local intensity parameters of the CH, group of this molecule were calculated and compared with the corresponding ones of ethylene.

ExoMol line lists – VIII. A variationally computed line list for hot formaldehyde

“…This may be due to the fact that AYTY sums over all lines in a given band whereas experiments generally only capture the strongest lines. Table 6 also shows the total band intensity for the 3.5 µm region compared to that by Brown et al (1979);Nakanaga et al (1982) and HITRAN. Our value is 13 % stronger than HITRAN, (matches the discrepancy for the ν1 and ν5 bands in Table 6), 18 % stronger than Nakanaga et al (1982) and 40 % stronger than that by Brown et al (1979).…”

“…Table 6 also shows the total band intensity for the 3.5 µm region compared to that by Brown et al (1979);Nakanaga et al (1982) and HITRAN. Our value is 13 % stronger than HITRAN, (matches the discrepancy for the ν1 and ν5 bands in Table 6), 18 % stronger than Nakanaga et al (1982) and 40 % stronger than that by Brown et al (1979). Absolute intensities and bands not available in the HITRAN database or literature can be evaluated against cross-sections.…”

“…Figure 7a compares the AYTY line list with a spectrum extracted from Fig. 3 of Nakanaga et al (1982) and scaled to match the AYTY line list. Good agreement is seen in both structure and position in the band with a slight drift occurring as an artifact from the extraction process.…”

“…Comparisons of H 2 CO partition functions as a function of temperature for this work, CDMS (Müller et al 2005) and those used in HITRAN (Fischer et al 2003). sections available from the PNNL-IR database (Sharpe et al 2004) and Nakanaga et al (1982) using a Gaussian profile with a HWHM (half-width-half-maximum) of 1.1849 cm −1 and 0.1120 cm −1 , determined from their respective experimental profiles. Figure 7a compares the AYTY line list with a spectrum extracted from Fig.…”

“…High-resolution, room-temperature formaldehyde spectra have been well-studied in the laboratory (Johns & McKellar 1975;Brown et al 1979;Nakanaga et al 1982;Nadler et al 1987;Cline & Varghese 1988;Reuter et al 1989;Poulin et al 1996;Theulé et al 2003); the early work was reviewed by Clouthier & Ramsay (1983). Currently, the major source of publicly available spectroscopic data on H2CO is the HITRAN database (Rothman et al 2013) which has recently been updated to include long-wavelength data from the CDMS database (Müller et al 2005).…”