Carbon 1s photoelectron spectroscopy of 1-pentyne conformers

The carbon 1s photoelectron spectrum of 1-pentyne has been recorded with resolution high enough that contributions from inequivalent carbon atoms can be determined. The spectrum is not well described by theoretical lineshape models that are based on either of the anti or the gauche conformations alone. An improved fit is obtained by combining the two single-conformer models, with the composition determined in the fit. This analysis yields 29 ± 3% anti and 71 ± 3% gauche conformers. This result is in agreement with results based on microwave spectroscopy and gas-phase electron diffraction.