Ultraviolet photoelectron spectroscopy of the phenide, benzyl and phenoxide anions, with ab initio calculations

In this and the accompanying paper we present a theoretical treatment and experimental study, respectively, of the phenomenon termed purely rotational coherence. This phenomenon has been demonstrated to be useful as a time domain means by which to obtain high resolution spectroscopic information on excited state rotational levels of large molecules [Felker et al., J. Phys. Chem. 90, 724 (1986); Baskin et al., J. Chem. Phys. 84, 4708 (1986)]. Here, the manifestations in temporally resolved, polarization-analyzed fluorescence of coherently prepared rotational levels in samples of isolated symmetric and asymmetric top molecules are considered. These manifestations, for reasonably large molecules at rotational temperatures characteristic of jet-cooled samples, take the form of polarization-dependent transients and recurrences with temporal widths of the order of tens of picoseconds or less. The transients, which arise from the thermal averaging of many single molecule coherences, are examined with respect to their dependences on molecular parameters (rotational constants, transition dipole directions) and experimental parameters (polarization directions and temperature). A physical picture of rotational coherence as a reflection of the time-dependent orientation of molecules in the sample is developed. And, the influence of rotational coherence in experiments designed to probe intramolecular energy flow is discussed. In the accompanying paper, we present experimental results for jet-cooled t-stilbene and anthracene. For t-stilbene we determine rotational constants for vibrational levels in the S1 electronic state (from the recurrences) and we monitor the trends in rotational coherence vs vibrational coherence as the total energy in the molecule increases.

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Purely rotational coherence effect and time‐resolved sub‐Doppler spectroscopy of large molecules. II. Experimental

We present theoretical proof that the nature of the interactions existent in the complexes formed between hydrogen fluoride and a series of π-systems (acetylene, ethylene, cyclopropene, cyclobutadiene, and benzene) and three-memebered-ring derivatives (cyclopropane and tetrahedrane) is that of a hydrogen bond between the hydrogen atom and the π-cloud. Geometric and energetic data and mainly the study of the topology of the electronic density within the frame of the theory of atoms in molecules established by Bader have been used for this analysis.

Unusual Hydrogen Bonds. H···π Interactions

Molecular complexes of the hydrogen halides studied by matrix isolation infrared spectroscopy

The results of picosecond‐resolved measurements of intramolecular vibrational‐energy redistribution (IVR) in jet‐cooled anthracene at different excess energies are presented. From these results, the nature of IVR as a function of vibrational energy, the relevant time scales for the process, and the details of pertinent vibrational couplings are determined.

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Dynamics of intramolecular vibrational‐energy redistribution (IVR). II. Excess energy dependence

Infrared spectra of hydrogen-bonded .pi. complexes between hydrogen halides and acetylene

Over 50 of the more intense transitions in the S1 excitation spectrum (0–2000 cm−1 of vibrational energy) of supersonic jet‐cooled anthracene are investigated using rotational band contour analysis, including computer simulations. This allows unambiguous assignment of the vibrational symmetries of all levels below 1100 cm−1 and many levels at higher energies, some of which were unassigned previously. Using complementary narrow‐band excitation and energy‐resolved detection techniques, a Fermi resonance at 755 cm−1 is thoroughly investigated to obtain the energy separation of the unperturbed states and the magnitude of the coupling matrix element. Levels which showed restricted or dissipative intramolecular vibrational‐energy redistribution in time‐resolved experiments (1380, 1420, and 1792 cm−1) are also studied.

Rotational band contour analysis of symmetries and interactions of vibrational levels in anthracene S1

Ultraviolet absorption spectra and photochemical rearrangements of benzyl and tropylium cations in solid argon

Etude de la nature de la redistribution d'energie vibrationnelle intramoleculaire dans des faisceaux supersoniques d'anthracene-D 1 -9 et d'anthracene D 10 . Comparaison avec l'anthracene-H 10 , en particulier sur le role des densites d'etats vibrationnels et des symetries moleculaires

Dynamics of intramolecular vibrational energy redistribution in deuteriated anthracenes: rotational band contour analysis and time-resolved measurements

Brian W. Keelan

Papers

Infrared spectra of hydrogen-bonded .pi. complexes between hydrogen halides and acetylene

Rotational band contour analysis of symmetries and interactions of vibrational levels in anthracene S1

Ultraviolet absorption spectra and photochemical rearrangements of benzyl and tropylium cations in solid argon

Dynamics of intramolecular vibrational energy redistribution in deuteriated anthracenes: rotational band contour analysis and time-resolved measurements

Absorption spectra and photochemistry of the toluene cation and benzyl radical in solid argon