High resolution Fourier-transform infrared spectroscopy of CHCl2F in supersonic jets: Analysis of ν3, ν7, and ν8

Abstract

The spectrum of CHCl2F (fluorodichloromethane, CFC 21) has been measured in the region of the ν3, ν7, and ν8 fundamentals (700–1300 cm−1, including the atmospheric window) by high resolution interferometric Fourier-transform spectroscopy [0.004 cm−1 bandwidth apodized, full width at half-maximum (FWHM)] in supersonic jet expansions with a rotational temperature of ∼70 K and at room temperature in static cells. The supersonic jet spectra allowed an analysis of the rotational fine structure to be started successfully and carried on to the room temperature spectra. Effective Hamiltonian constants have been obtained with accurate band centers for the two most abundant isotopes CH35Cl2F(CH35Cl37ClF), ν̃8=807.1749(805.0492) cm−1, ν̃3=1079.4276(1079.3893) cm−1, and ν̃7=1239.1940(1238.6884) cm−1. Excited state rotational constants and improved ground state rotational constants including quartic centrifugal distortion in the Watson Hamiltonian are reported as well as hot bands and further bands in anharmonic resonance with the fundamentals. The results are important for and discussed in relation to simulations of atmospheric absorption, line coincidences with CO2 lasers for sub-Doppler spectroscopy and infrared (IR) multiphoton excitation and anharmonic intramolecular dynamics.