Portion of the 2DF spectrum of a benzene discharge, shown in full in Ref. 20. A LIF excitation spectrum of 1PPR, obtained by integrating the horizontal rectangle between the emission wavelengths of 473.5 and 480 nm, is shown in the bottom panel. In the right panel is a low resolution 1PPR origin DF spectrum, obtained by horizontally integrating the vertical rectangle centered on an excitation wavelength of 476 nm. The relative intensity of the origin band, being four to six times stronger than any other vibronic feature, indicates that the electronic transition is largely “vertical.”
LIF spectrum of 1PPR in observed from a discharge of 3-phenyl-1-propyne. Frequencies relative to the origin wavenumber are indicated above many of the observed bands. Shown in higher resolution above the main spectrum contain are two congested regions which are important to securing assignments. Table I contains assignments.
DF spectrum from the level of 1PPR, plotted relative to the laser frequency. Vibrational frequencies are indicated above many of the observed bands. The breakout figure shows a highly congested region which contains many important assignments. The full assignment is given in Table II.
Structure of 1PPR, and beneath, a cartoon depiction of the five orbitals and electrons used in the optimization of the geometry of 1PPR. The electronic transition is a combination of the HOMO-LUMO and SHOMO-HOMO transitions. The labels shown are used to describe normal modes in the text. Indicated structural parameters are listed in Table III.
Duschinsky matrices of the (top) and vibrational modes of 1PPR. Each matrix element is equal to the scalar product of normal mode displacement vector with mode of . The excited state numbering is provided in both normal order and using the numbering for the same vibrational mode (see text).
SVLF spectra of the indicated modes of 1PPR. Excitation frequencies shown at right are from Fig. 2.
DF spectra of the indicated modes of 1PPR. Excitation frequencies shown at right are from Fig. 2.
Excitation frequencies, measured relative to the origin wavenumber , and assignments of 1PPR shown in Fig. 2. Unadorned assignments have either been probed explicitly by DF spectroscopy or are combination bands involving modes thus identified; square brackets adorn assignments that are best guesses for levels that have not been probed by DF, and blanks indicate bands that were not probed by DF and for which there is no obvious assignment. The least certain assignments are further indicated by “?”. Assignments for levels that may overlap, or be in Fermi resonance, are separated by “”. All frequencies in .
Frequencies and assignments of transitions in the origin DF spectrum of 1PPR shown in Fig. 3. Unadorned assignments are derived from levels probed explicitly by DF; adornments  indicate levels that involve modes whose excited state analogs were not probed directly by DF; the least certain assignments are further indicated by “?”.
Results of 1PPR geometry optimizations. Labels of structural parameters follow Fig. 4. Bond lengths are in angstroms. All dihedral angles are 0° or 180°.
Vibrational frequencies of the and states of 1PPR, and maximum Duschinsky matrix elements . Unadorned experimental frequencies indicate modes that have been probed directly by DF; adornments [ ] indicate the most likely assignments for modes not directly probed by DF; the least certain assignments are further indicated by “?”. Vibrations are described using ; ; ; ; and . “” indicates the phenyl ring.
Summary of assignments of SVLF spectra assigned to modes. Assignments in parentheses are more tentative. Levels in Fermi resonance are linked by “”. All frequencies in .
Summary of assignments of SVLF spectra assigned to modes. Assignments in parentheses are more tentative. All frequencies in .
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