HeI photoelectron spectroscopic study of vitamin A and its derivatives

HeI photoelectron spectra of vitamin A (all-trans-retinol and its two deriv atives (13-cis-retinoic acid and all-trans-retinoic acid) were observed in the gas phase for the first time, by using an infrared heating device which was developed in this laboratory. The first vertical ionization energies ( I-obs) were determined to be 6.95, 7.10 and 7.20 eV, respectively. Several higher ionization energies were also observed. The valence electronic struc tures associated with the observed ionization energies were elucidated by a b initio calculations carried out in the present study. (C) 2000 Elsevier S cience B.V. All rights reserved.