Two-Color Resonant Two-Photon Mass-Analyzed Threshold Ionization of 2,4-Difluoroanisole and the Additivity Relation of Ionization Energy.

We used the two-color resonant two-photon ionization and mass-analyzed threshold ionization spectroscopic techniques to record the vibronic, photoionization efficiency, and cation spectra of 2,4-difluoroanisole. The cation spectra were obtained through ionization via seven intermediate vibronic states, which involved out-of-plane ring-F, in-plane ring-F, and ring-OCH bending vibrations as well as in-plane ring deformation vibrations. The band origin of the S ← S electronic transition of 2,4-difluoroanisole appeared at 35 556 ± 2 cm, and the adiabatic ionization energy was determined to be 67 568 ± 5 cm.

Cation Vibrations of 1-Methylnaphthalene and 2-Methylnaphthalene through Mass-Analyzed Threshold Ionization Spectroscopy.

Vibrationally resolved cation spectra of 1-methylnaphthalene (1MN) and 2-methylnaphthalene (2MN) were obtained using the two-color resonant two-photon mass-analyzed threshold ionization (MATI) spectroscopy. MATI spectra were obtained through ionization via several intermediate vibronic levels. Due to hindrance effect, no spectral features related to methyl torsion were observed in the MATI spectra of 1MN.

Rydberg state mediated multiphoton ionization of (η-CH)(η-CH)Cr: DFT-supported experimental insights into the molecular and electronic structures of excited sandwich complexes.

The resonance-enhanced multiphoton ionization (REMPI) of a mixed sandwich complex has been achieved for the first time when exciting (η7-C7H7)(η5-C5H5)Cr via the Rydberg 4pz state. The REMPI spectrum is indicative of unexpectedly small changes of the sandwich geometry on excitation. Time-dependent DFT calculations reveal fine effects of the ligand nature on the molecular and electronic structure variations accompanying electronic excitation.

Fine Substituent Effects in Sandwich Complexes: A Threshold Ionization Study of Monosubstituted Chromium Bisarene Compounds.

Mass-analyzed threshold ionization spectra of jet-cooled [(η(6) -PhMe)(η(6) -PhH)Cr] and [(η(6) -Ph2 )(η(6) -PhH)Cr] reveal with unprecedented accuracy the effects of methyl and phenyl groups on the electronic structure of bis(η(6) -benzene)chromium. These "pure" substituent effects allow quantitative experimental determination of the ionization energy changes caused by the mutual substituent influence in bisarene systems. Two types of such influence have been revealed for the first time in bis(η(6) -toluene)chromium.

Identification of four rotamers of m-methoxystyrene by resonant two-photon ionization and mass analyzed threshold ionization spectroscopy.

We report the vibronic and cation spectra of four rotamers of m-methoxystyrene, recorded by using the two-color resonant two-photon ionization and mass-analyzed threshold ionization techniques. The excitation energies of the S1← S0 electronic transition are found to be 32 767, 32 907, 33 222, and 33 281 cm(-1), and the corresponding adiabatic ionization energies are 65 391, 64 977, 65 114, and 64 525 cm(-1) for these isomeric species. Most of the observed active vibrations in the electronically excited S1 and cationic ground D0 states involve in-plane ring deformation and substituent-sensitive bending motions.

Rotamers of 3,4-difluoroanisole studied by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy.

We reported the vibronic and cation spectra of 3,4-difluoroanisole. The band origins of the S(1) ←S(0) electronic transition of the cis and trans rotamers appear at 35,505 ± 2 and 35,711 ± 2 cm(-1) and the adiabatic ionization energies are determined to be 67,780 ± 5 and 68,125 ± 5cm(-1), respectively. Most of the observed active vibrations in the electronically excited S(1) and cationic ground D(0) states mainly involve in-plane ring deformation and substituent-sensitive bending vibrations.