The nu(5) antisymmetric stretching mode of linear C(7) revisited in high resolution.

The nu(5) antisymmetric stretching mode of the linear carbon cluster C(7) has been revisited using a sensitive high-resolution spectrometer, including an external-cavity quantum cascade laser covering the range of interest of 1894-1901 cm(-1). 50 transitions of the nu(5)-band have been recorded and analyzed together with 45 transitions of the nu(4)-band measured by Neubauer-Guenther et al. [J. Chem. Phys. 127, 014313 (2007)]. We determined the band centers, rotational and centrifugal constants very precisely. In addition, 29 hot band transitions have been measured and tentatively assigned to the nu(5)+nu(11)-nu(11) hot band. A global fit of the hot bands nu(5)+nu(11)-nu(11) and nu(4)+nu(11)-nu(11) is presented. Derived l-type doubling constants allow for an experimental estimation of the nu(11)-band center.