We report high-resolution ((Formula presented.) 0.001 cm−1) Fourier Transform Infrared spectra of fluoroform (CHF3) including the pure rotational (far infrared or THz) range (28–65 cm−1), the ν3 fundamental ((Formula presented.) = 700.099 cm−1), as well as the associated “hot’ band 2ν3 − ν3 ((Formula presented.) = 699.295 cm−1) and the ‘atmospheric window’ range 1100–1250 cm−1 containing the strongly coupled polyad of the levels ν2, ν5 and ν3 + ν6, at room temperature and at 120 K using the collisional cooling cell coupled to our Bruker IFS 125 HR prototype (ZP2001) spectrometer and Bruker IFS 125 HR ETH-SLS prototype at the Swiss Light Source providing intense synchrotron radiation. The pure rotational spectra provide new information about the vibrational ground state of CHF3, which is useful for further analysis of excited vibrational states. The ν3 fundamental band is re-investigated together with the corresponding ‘hot’ band 2ν3 − ν3 leading to an extension of the existing line lists up to 4430 transitions with Jmax = 66 for ν3 and 1040 transitions with Jmax = 43 for 2ν3 − ν3. About 6000 transitions were assigned to rovibrational levels in the polyad ν2/ν5/ν3 + ν6 with Jmax = 63 for ν2 ((Formula presented.) = 1141.457 cm−1), Jmax = 63 for ν5 ((Formula presented.) = 1157.335 cm−1) and Jmax = 59 for ν3 + ν6 ((Formula presented.) = 1208.771 cm−1)(Kmax = Jmax in each case). The resonance interactions between the ν2, ν5 and ν3 + ν6 states have been taken into account providing an accurate set of effective hamiltonian parameters, which reproduce the experimental results with an accuracy close to the experimental uncertainties (with a root mean square deviation drms = 0.00025 cm−1). The analysis is further extended to the ν4 fundamental ((Formula presented.) = 1377.847 cm−1) interacting with 2ν3 ((Formula presented.) = 1399.394 cm−1). The results are discussed in relation to the importance of understanding the spectra of CHF3 as a greenhouse gas and as part of our large effort to measure and understand the complete spectrum of CHF3 from the far-infrared to the near-infrared as a prototype for intramolecular quantum dynamics and rovibrational energy redistribution.
ASJC Scopus subject areas
- Molecular Biology
- Condensed Matter Physics
- Physical and Theoretical Chemistry