A multispectrum analysis of the ν1 band of H 12C 14N: Part II. Air- and N 2-broadening, shifts and their temperature dependences

Abstract

Air- and N 2-broadening, air- and N 2-pressure-induced shift coefficients and the temperature dependence exponent of the broadening coefficients and the temperature dependent coefficient of pressure-induced shifts have been determined for transitions of the ν 1 band of H 12C 14N from 39 laboratory absorption spectra recorded at 0.005 and 0.008 cm −1 resolutions with two different Fourier transform spectrometers. The parameters were retrieved from the multispectrum nonlinear least-squares fits to the 3200– 3400 cm −1 region of spectra recorded at temperatures between +26°C and −60°C. Pure samples of HCN in a 19.95 cell and a 0.958 cm cell at room temperature as well as lean mixtures of HCN in N 2 or dry air in a coolable cell with a 50 cm absorption path were used in the experiments. Line parameters for N 2 broadening were determined by fitting 27 spectra simultaneously while air-broadening parameters were quantified from simultaneous fits to 22 spectra. The average ratio and the standard deviation of the room-temperature air- to N 2-broadening coefficient of lines with assignments between P(29) and R(28) are 0.904±0.001. Pressure-induced shift coefficients at 296 K are all negative with values between 0 and ∼−0.006 cm −1 atm −1 and different rotational dependences in the P- and R-branches. Differences between our results, previous measurements and the parameters that are reported in the 2000 edition of HITRAN (HIgh-resolution TRANsmission) database are quantified and discussed.