Low-temperature measurements of HCN broadened by N2 in the 14-μm spectral region

Half-width and pressure-induced shift coefficients; the temperature-dependence exponents of the half-widths and the temperature-dependence coefficients of pressure-induced shifts have been measured for N2-broadened transitions in the ν2 band of HCN. Line positions and intensities were also determined. A total of 34 laboratory absorption spectra, recorded at 0.002-0.005 cm−1 resolution with two different Fourier transform spectrometers, were used in the determination of the spectral line parameters. The total pressures of the HCN-N2 samples ranged from less than 1 torr up to nearly 1 atm, and temperatures were between 211 and 300 K. A multispectrum nonlinear least-squares fitting technique employing a modified Voigt line profile, including speed dependence and line mixing via the off-diagonal relaxation matrix formulation, was used in the analysis. Speed-dependence parameters were determined in the P and R branches of the ν2 band of H12C14N, and in the ν2 Q branches of H12C14N and H13C14N the off-diagonal relaxation matrix elements that characterize line mixing were included in the analysis to fit the data. Present results are compared with previous measurements reported in the literature.