Naphthyl Radical:  Negative Ion Photoelectron Spectroscopy, Franck−Condon Simulation, and Thermochemistry

Abstract

The naphthyl anion (C10H7 -, naphthalenide) is prepared in a flow tube reactor by proton transfer between NH2 - and naphthalene (C10H8). The photoelectron spectrum of this anion is measured at a fixed laser wavelength of 364 nm. A single electronic band is observed, corresponding to the neutral naphthyl radical (C10H7, naphthalenyl). The Franck−Condon profiles for both 1-naphthyl (α-naphthyl) and 2-naphthyl (β-naphthyl) are simulated on the basis of density functional theory calculations of the vibrational frequencies and normal coordinates. Issues involving Franck−Condon simulations for large polyatomic molecules and Duschinsky rotation are discussed, and improved Franck−Condon simulation algorithms are presented. Comparison of the Franck−Condon simulations with the photoelectron spectrum shows that the observed band is predominantly due to the 1-naphthyl isomer, consistent with previous measurements showing the 1-naphthyl anion as more stable than the 2-naphthyl anion. The observed electron affinity of the 1-naphthyl radical is EA0(1-C10H7) = 1.403 ± 0.015 eV. On the basis of an evaluation of literature data, the recommended gas-phase acidity of naphthalene is Δacid H 298(1-C10H7−H) = 1649 ± 14 kJ/mol and the recommended bond dissociation energy of naphthalene is DH 298(1-C10H7−H) = 472 ± 14 kJ/mol.

Anion Photoelectron Spectroscopy of C3N− and C5N−

“…The vibrational temperature and the known calculated and experimental anion and neutral vibrational frequencies were used as inputs into the PESCAL program by Ervin and co-workers. [44][45][46] This program uses the recursion relation method of Hutchisson 47 to calculate the FC factors and output a simulated photoelectron spectrum. Figure 1 compares the SEVI spectrum with the stick FC simulation of the X 2 Σ + r X 1 Σ + transition.…”

Internal conversion outcompetes autodetachment from resonances in the deprotonated tetracene anion continuum

“…This conclusion is consistent with other electrospray studies showing that Please do not adjust margins Please do not adjust margins polarity-matched solvents and solutes tend to produce statistical/thermodynamic gas-phase products. 60,61 In addition, vibrationally-resolved photodetachment spectroscopy, 62,63 and mass spectrometry on the naphthyl anion, 64 as well as ab initio calculations on a range of PAH species, 65,66 indicate a very strong propensity to remove the most weakly bound proton during 'soft' anion formation. Based on the above assignment of the deprotontation site, the prompt detachment spectrum can be assigned.…”

Low-energy photoelectron imaging spectroscopy of nitromethane anions: Electron affinity, vibrational features, anisotropies, and the dipole-bound state

“…25,26 Except for the torsional vibration for internal rotation around the CN bond, which is discussed separately in Sec. IV C, the FCFs were calculated in the independent harmonic oscillator approximation with full treatment of the Duschinsky rotation 27 of the normal mode eigenvectors between the anion and neutral, using the SharpRosenstock-Chen recursion method.…”

“…IV C, the FCFs were calculated in the independent harmonic oscillator approximation with full treatment of the Duschinsky rotation 27 of the normal mode eigenvectors between the anion and neutral, using the SharpRosenstock-Chen recursion method. 25,28,29 Additional details of the Franck-Condon simulations described here are provided in the Supplementary Information. 49 The vibrational frequencies for neutral CH 3 NO 2 ͑14 of the 15 modes, i.e., excluding the torsion͒ were taken from the experimental infrared/Raman fundamental frequencies 30 and substituted for the calculated values.…”

“…The calculated geometry changes between the anion and neutral are given in Table I, presented as the K ជ Љ displacement vector in the anion normal coordinate frame as defined elsewhere. 25,29 The signs of the Cartesian displacement vectors are arbitrary in the harmonic oscillator approximation, but need to be defined self-consistently for the Duschinsky rotation calculations. We have chosen the direction of the normal coordinates for each mode such that the B rotational constant of the molecule decreases ͑I yy component of the moment of inertia increases͒ for a positive displacement.…”