Lines intensities in the ν4 band of NH3 at low temperature

Line intensities in the ν 4 band of NH 3 have been measured at low temperature (235 K) for some selected lines in the P P and R P-branches of ν 4 band using a high resolution Fourier transform spectrometer. These line intensities were obtained using the method of multispectrum fitting to the measured shapes of the lines. The J and K quantum numbers dependencies are discussed. The analysis of the results yields effective transition moments and vibrational band strengths of the symmetric and antisymmetric components of the ν 4 band.