New High-Resolution Analysis of the ν7 and ν9 Fundamental Bands of trans-Formic Acid by Fourier Transform Infrared and Millimeter-Wave Spectroscopy

FTIR and millimeter wave investigation of the 71 and 91 states of formic acid HCOOH and H13COOH

“…(3), that is, including all leading and higher order terms, as far as they can be determined, in H 12 of a general form (3). Typically the difficulties encountered when using unreduced Hamiltonians are not important because in most investigations only a few interaction parameters are needed to match the observed transition frequencies, and these are well determined.…”

“…Many of the parameters derived in [3] are highly correlated and, consequently, the parameter uncertainties are unusually large. Since the properties of the m 7 and m 9 bands in HCOOH and H 13 goal of the current work was thus to consider the unsatisfactory correlations determined for HCOOH [3] and to determine a more accurate set of parameters for this species, too. With this object in mind, a new FTIR measurement with higher absorption was carried out for HCOOH and new millimeter wave (MMW) data in the region 115-370 GHz were included.…”

“…Although the m 7 and m 9 bands of the parent species have been investigated in great detail [3,5], there is still a problem concerning the resulting parameters. Many of the parameters derived in [3] are highly correlated and, consequently, the parameter uncertainties are unusually large.…”

“…The interaction is somewhat weaker in the case of both HCOOD and DCOOD. The rovibrational energy levels of the 7 1 and 9 1 states have been studied both in the millimeter and submillimeter regions and by means of high resolution FTIR spectroscopy for the parent and all three D substituted isotopomers [2][3][4][5][6][7]. A comprehensive list of references to spectroscopic studies of formic acid can be found in Ref.…”

“…A comprehensive list of references to spectroscopic studies of formic acid can be found in Ref. [3].…”