Effect of noncovalent interactions on conformers of the n-butylbenzene monomer studied by mass analyzed threshold ionization spectroscopy and basis-set convergent ab initio computations

TY - JOUR

T1 - Effect of noncovalent interactions on conformers of the n-butylbenzene monomer studied by mass analyzed threshold ionization spectroscopy and basis-set convergent ab initio computations

AU - Tong, Xin

AU - Cerny, Jiri

AU - Mueller-Dethlefs, Klaus

AU - Dessent, Caroline EH

PY - 2008/7/3

Y1 - 2008/7/3

N2 - Two conformational isomers of the aromatic hydrocarbon n-butylbenzene have been studied using two-color MATI (mass analyzed threshold ionization) spectroscopy to explore the effect of conformation on ionization dynamics. Cationic states of gauche-conformer III and anti- conformers IV were selectively produced by two-color excitation via the respective S, origins. Adiabatic ionization potentials of the gauche- and anti-conformations were determined to be 70146 and 69872 +/- 5 cm(-1) respectively. Spectral features and vibrational modes are interpreted with the aid of MP2/cc-pVDZ ab initio calculations, and ionization-induced changes in the molecular conformations are discussed. Complete basis set (CBS) ab initio studies at MP2 level reveal reliable energetics for all four n-butylbenzene conformers observed in earlier two-color REMPI (resonance enhanced multiphoton ionization) spectra. For the So state, the energies of conformer III, IV and V are above conformer I by 130, 289, 73 cm(-1), respectively. Furthermore, the combination of the CBS calculations with the measured REMPI, MATI spectra allowed the determination of the energetics of all four conformers in the S-1 and D-0 states.

AB - Two conformational isomers of the aromatic hydrocarbon n-butylbenzene have been studied using two-color MATI (mass analyzed threshold ionization) spectroscopy to explore the effect of conformation on ionization dynamics. Cationic states of gauche-conformer III and anti- conformers IV were selectively produced by two-color excitation via the respective S, origins. Adiabatic ionization potentials of the gauche- and anti-conformations were determined to be 70146 and 69872 +/- 5 cm(-1) respectively. Spectral features and vibrational modes are interpreted with the aid of MP2/cc-pVDZ ab initio calculations, and ionization-induced changes in the molecular conformations are discussed. Complete basis set (CBS) ab initio studies at MP2 level reveal reliable energetics for all four n-butylbenzene conformers observed in earlier two-color REMPI (resonance enhanced multiphoton ionization) spectra. For the So state, the energies of conformer III, IV and V are above conformer I by 130, 289, 73 cm(-1), respectively. Furthermore, the combination of the CBS calculations with the measured REMPI, MATI spectra allowed the determination of the energetics of all four conformers in the S-1 and D-0 states.

KW - DER-WAALS COMPLEXES

KW - ENERGY PHOTOELECTRON-SPECTROSCOPY

KW - ZEKE

KW - RESOLUTION

KW - CATION

KW - CLUSTERS

KW - SPECTRA

KW - PROPYLBENZENE

KW - CONFORMATION

KW - ENERGETICS

UR - http://www.scopus.com/inward/record.url?scp=53349099749&partnerID=8YFLogxK

U2 - 10.1021/jp710997q

DO - 10.1021/jp710997q

M3 - Article

SN - 1089-5639

VL - 112

SP - 5866

EP - 5871

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

IS - 26

ER -