Photoelectron spectroscopy [1] constitutes a fast method. Mixtures of conformers can sometimes be detected in PE spectra if orbital energies depend on a parameter of the conformational change, e.g. a dihedral angle, and differences in orbital energies of conformers are large enough. In such a case, there are usually more ionization bands in the low energy part of the PE spectrum than there are orbitals in the molecule from which the ionizations could arise. The measured spectrum for 1 is not of this sort.