High resolution FT-IR spectra of the nu(1), nu(2), and nu(3) bands of (HCP)-C-12 and of the nu(1) and nu(2) bands of (HCP)-C-13

A sample of HCP (phosphaethyne) was synthesized by pyrolysis of CH3PCl2 (dichloromethylphosphane). (HCP)-C-13 was present in natural abundance. High resolution spectra were measured with a BRUKER IFS 120 HR Fourier transform spectrometer using a 3-m absorption cell, and a White-type cell with absorption path lengths up to 19.68 m. The wavenumber regions measured were 400-725, 1200-1850 and 2500-3600 cm(-1) with resolutions of 0.0018, 0.0024 and 0.0048 cm(-1), respectively. In the lowest wavenumber region, the v(2) fundamental band, hotbands from v(2) = 1,2,3, and v(3) = 1, as well as one Fermi-resonance induced band, (v(1)v(2)(2)v(3))=(00(Oe)1)<--(01 O-le), were assigned and analysed. In the second region, the fundamental band v(3), its hot band from v(2) = 1, and the overtone of v(2) and its hot bands could be measured, and in the third region, v(1) and its hot bands. The fundamental and overtone bands of the bending vibration of (HCP)-C-13, and its hotbands from v(2) = 1 and 2, as well as the vi fundamental were also assigned and analysed. The bands observed for the first time in this work are: for (HCP)-C-12: (011)-(001), (001)-(010), (030)-(020), (011)-(010), (040)-(030), and for (HCP)-C-13: (020)-(010), (020)-(000). Spectroscopic constants including Fermi resonance parameters for (HCP)-C-12 and (HCP)-C-13 of the effective Hamiltonian for linear molecules are given. (C) 1997 Elsevier Science B.V.