Spectral shifts and structures of phenol...Ar(n) clusters.

A laser spectroscopic investigation of phenol...

Mass analyzed threshold ionization spectra of phenol...Ar2: ionization energy and cation intermolecular vibrational frequencies.

The phenol(+)...

Dissociation energetics of the phenol(+)⋯Ar(2) cluster ion: The role of π→H isomerization.

The dissociation energetics in the phenol(+)⋯Ar(2)(2π) cluster ion have been investigated using photoionization efficiency and mass analyzed threshold ionization spectroscopy. The appearance energies for the loss of one and two Ar atoms are determined as ∼210 and ∼1115 cm(-1), respectively. The difference between the appearance energy for the first Ar ligand in phenol(+)⋯Ar(2)(2π) and the dissociation energy of the phenol(+)⋯Ar(π) dimer (535cm(-1)) is explained by the isomerization of one π-bound Ar ligand to the OH binding site (H-bond) upon ionization.

Fragmentation energetics of the phenol(+)···Ar(3) cation cluster.

The various dissociation thresholds of phenol(+)···Ar(3) complexes for the consecutive loss of all three Ar ligands were measured in a molecular beam using resonant photoionization efficiency and mass analyzed threshold ionization spectroscopy via excitation of the first excited singlet state (S(1)). The adiabatic ionization energy is derived as 68077 ± 15 cm(-1). The analysis of the dissociation thresholds demonstrate that all three Ar ligands in the neutral phenol···Ar(3) tetramer are attached to the aromatic ring via π-bonding, denoted phenol···Ar(3)(3π).

A novel experimental system of high stability and lifetime for the laser-desorption of biomolecules.

A novel laser desorption system, with improved signal stability and extraordinary long lifetime, is presented for the study of jet-cooled biomolecules in the gas phase using vibrationally resolved photoionization spectroscopy. As a test substance tryptophane is used to characterize this desorption source. A usable lifetime of above 1 month (for a laser desorption repetition rate of 20 Hz) has been observed by optimizing the pellets (graphite/tryptophane, 3 mm diameter and 6 mm length) from which the substance is laser-desorbed.

Determination of the binding energies in aromatic clusters: resonance-enhanced multi- photon ionization and mass analyzed threshold ionization investigation of the dichlorobenzene-argon complexes.

Resonance-enhanced multi-photon ionization (REMPI) and mass-analyzed threshold ionization (MATI) spectroscopic investigations were applied to the van der Waals complexes of the three dichlorobenzene isomers with argon. From the REMPI spectra it is concluded that the argon atom is shifted towards the chlorine atoms during excitation for the ortho and the meta isomers while it stays in the middle of the ring for the para isomer. From the MATI spectra it was possible to determine the binding energies in the ion ground state to 617 cm(-1) -/+ 15 cm(-1), 529 cm(-1) -/+ 125 cm(-1) and 581 cm(-1) -/+ 76 cm(-1) for the para, the meta and the ortho isomer, respectively.

REMPI and MATI spectroscopic investigation of dichlorobenzene-argon complexes: determination of the binding energies.

REMPI and MATI spectroscopic investigations were applied to van-der-Waals complexes of the three dichlorobenzene isomers with argon. From the REMPI spectra it is concluded that the argon atom is shifted towards the chlorine atoms during excitation for the ortho and the meta isomer while it stays in the middle of the ring for the para isomer. From the MATI spectra it was possible to determine the binding energies in the ion ground state as 617 +/- 15 cm(-1), 529 +/- 125 cm(-1) and 581 +/- 76 cm(-1) for the para, the meta and the ortho isomer, respectively.

Detailed analysis of the cation ground state of three dichlorobenzenes by mass analyzed threshold ionization spectroscopy.

Two color resonant mass analyzed threshold ionization (MATI) spectroscopy was applied in order to investigate the ionic properties of the structural isomers of dichlorobenzene above the ionization threshold. A detailed analysis of the vibrational properties of the two main chlorine isotopomers of each isomer was performed resulting in a precise picture of the vibrational states in the cation ground states. The general features of the two investigated isotopomers turned out to be quite similar, although some vibrational modes are slightly different up to a few wavenumbers, except for the 6b normal mode of p-dichlorobenzene.

Mass analyzed threshold ionization spectroscopy of o-, m-, and p-dichlorobenzenes. Influence of the chlorine position on vibrational spectra and ionization energy.

For the first time, vibrational spectra of the 35Cl2 and 35Cl37Cl isotopomers of o-, m-, and p-dichlorobenzene cations in the electronic ground state have been measured via S1 intermediate states by mass analyzed threshold ionization (MATI) spectroscopy. Additionally, ab initio calculations at DFT (density functional theory), CIS (configuration interaction singles), and CASSCF (complete active space self-consistent field) levels of theory have been conducted to compare experimental findings with theory. From the MATI spectra, adiabatic ionization energies of the ortho, meta, and para isomers have been determined to be the same for each pair of investigated isotopomers to 73,237 +/- 6, 72,191 +/- 6, and 73,776 +/- 6 cm(-1), respectively.