Observation of hot bands in the infrared spectrum of H2CO

A new “spectroscopic” potential energy surface for formaldehyde in its ground electronic state

“…We sus- forms in extrapolations to higher J values, we have generated the ro-vibrational energies for J = 6. Comparison with the available experimental term values 29,30,32 yields a rms error of 0.08 cm −1 for 167 J = 6 ro-vibrational term values, all below 4100 cm −1 . This indicates that the refined PES remains reasonable for moderate extrapolations to somewhat higher J values.…”

“…Perrin et al 29 published a very accurate synthetic line list covering the band systems (ν 2 , ν 3 , ν 4 , ν 6 ) and (ν 1 , ν 2 + ν 3 , ν 2 + ν 4 , ν 2 + ν 6 , 2ν 3 , ν 3 + ν 4 , ν 3 + ν 6 , 2ν 4 , ν 4 + ν 6 , ν 5 , 2ν 6 ) in the 5.7 μm and 3.6 μm regions, respectively. Perez et al 32 measured a set of hot transitions belonging to the bands ν 4 − ν 4 , ν 1 + ν 4 − ν 4 , and ν 4 + ν 5 − ν 4 . These transitions involve states not present in the line compilations of Tchana et al 30 and Perrin et al 29 For our input dataset, we selected 492 energy levels with J ≤ 5 from Refs.…”

Vibrational levels of formaldehyde: Calculations from new high precision potential energy surfaces and comparison with experimental band origins

“…The contributions of various corrections to vibrational levels and our final ab initio results are collected in Table 5. The experimental energy levels are taken from refs [77] [78] [79], and [80].…”

“…where n is number of ν 2 quanta. ), a -from ref [81], b -from ref [78], c -from ref [77], dfrom ref [79], with one decimal place from ref [80]. #) Rel.= relativistic; T(Q) = CCSDT(Q) -CCSD(T) correlation; Q+6Z = quadruple Δ Q+6Z correction (see text for explanation).…”

Laser diode photoacoustic and FTIR laser spectroscopy of formaldehyde in the 2.3 μm and 3.5 μm spectral range

“…However, the spectra of H 2 CO in the near infrared spectral range are extremely difficult to analyse because of multiple strong resonances. Nevertheless, the infrared spectrum has been studied in detail by various techniques [13][14][15][16].…”