title: On the ultrafast photo-induced dynamics of α-terpinene.
abstract: The ultrafast relaxation pathway of α-terpinene was studied by photoionization-photoelectron spectroscopy for a range of excitation conditions. Time-resolved spectra were obtained upon optical excitation with ultrashort laser pulses at 5.56 eV, 4.96 eV, 4.76 eV, and 4.56 eV, followed by ionization with 3.06 eV pulses. The experiments yielded spectra of the initially excited state, which decays with a time constant of 66 fs, independent of the excitation wavelength. We also observed a sequential series of Rydberg peaks, including the s, p, and d states with n = 3-6, which capture the travel times on the ensuing reaction path. There is no statistically significant dependence of the travel time on the excitation energy. A comparison of the time-dependent signals with those of the un-substituted parent molecule, 1,3-cyclohexadiene, shows that the substituents on α-terpinene slow the reaction down by a factor of about 2.
authors.affiliation: Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Christine C
authors.initials: CC
authors.lastname: Pemberton
authors.affiliation: Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Weber
mesh_terms: D000081005:Cyclohexane Monoterpenes; D053138:Cyclohexenes / Q000737:chemistry / Q000528:radiation effects; D015394:Molecular Structure; D039821:Monoterpenes / Q000737:chemistry / Q000528:radiation effects*; D056951:Photoelectron Spectroscopy; D013997:Time Factors
chemical_list: D000081005:Cyclohexane Monoterpenes; D053138:Cyclohexenes; D039821:Monoterpenes; C018669:gamma-terpinene; C034005:1,3-cyclohexadiene