A jet-cooled infrared spectrum of the formic acid dimer by cavity ring-down spectroscopy

An infrared absorption spectrum of formic acid dimer (HCOOH)2 in the C–H stretching region has been observed in a supersonic jet by cavity ring-down spectroscopy. In total six vibrational bands have been identified in the region 2800–2950 cm−1, and the center frequency and relative intensity for each of them, as well as its tentative assignment, has been determined. Comparison with previous studies has shown that there is a discrepancy with regard to the assignment of the O–H stretching band.