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Articles you may be interested inProtonation effect on the electronic properties of 2-pyridone monomer, dimer and its water clusters: A theoretical study J. Chem. Phys. 140, 024315 (2014); 10.1063/1.4859255 Magnetocaloric effect and spin reorientation transition in single-crystal Er 2 ( Co 0.4 Fe 0.6 ) 17 J. Appl. Phys. 105, 07A918 (2009); 10.1063/1.3063669Effect of oxygen adsorption on the structure and spin-reorientation transition of Fe films on Cu (1 1 25) Rotationally resolved ultraviolet spectroscopy of indole, indazole, and benzimidazole: Inertial axis reorientation in the S 1(1 L b )←S 0 transitions Rotationally resolved fluorescence excitation spectra of two vibronic bands in the SI <-So electronic transition of2-hydroxypyridine (2HP), and of the corresponding bands in the hydroxy-deuterated molecule, have been obtained. A comparison of the rotational constants of the two molecules shows that the two bands both originate in the zero-point vibrati6nallevel of the planar keto tautomer of2HP, 2-pyridone (2PY), and terminate in different zero-point levels of 2PY that have different out-of-plane eqUilibrium geometries at nitrogen. Additionally, all four bands exhibit "anomalous" rotational line intensities that are shown to result from an in-plane inertial axis reorientation which occurs on absorption of the photon. Likely atomic displacements that are responsible for this "rotational" Duschinsky effect, which may have significant dynamical consequences in 2PY and other molecules, are discussed.

Rotationally resolved S1←S0 electronic spectra of aniline and its single atom van der Waals complex with argon (An–Ar) have been observed. Analysis of these spectra leads to a determination of the vibrationally averaged structures of the bare molecule and the complex in the two electronic states. Aniline itself is pyramidally distorted at the NH2 group in the S0 state. Attachment of the Ar atom on the side of the ring opposite the two N–H bonds converts the symmetric double well along the inversion coordinate into an asymmetric one, in the ground state. The excited state is quasiplanar along this coordinate. Analyses of the spectra of An–Ar at higher energies in the S1 state provide a probe of the vibrational predissociation (VP) behavior of the complex. We observe in these spectra line broadenings and spectral perturbations from which the important role of intra–intermolecular mode mixing (i.e., IVR) in promoting the VP process is elucidated.

Rotationally resolved S 1 r S 0 fluorescence excitation experiments have been performed on a solute-solvent complex of indole and water in a molecular beam. The results show that the complex whose S 1 r S 0 origin is shifted by 132 cm -1 below the bare molecule origin is a 1:1 complex, with the water molecule linked to the indole frame via a quasi-linear N-H‚‚‚OH 2 σ hydrogen bond. The results also show that both the position and the orientation of the attached water molecule change when the photon is absorbed. The properties of the intermolecular potential-energy surfaces that govern these motions in both electronic states are derived from an analysis of the high-resolution spectrum.

The properties of the three lowest singlet electronic states (ground, (1)L(b), and (1)L(a) states) of indole (C(8)H(7)N) have been calculated with second-order approximate coupled-cluster theory (CC2) within the resolution-of-the-identity approximation. Refined electronic energies at the CC2 optimized structures and transition dipole moments were calculated using a density functional theory multi-reference configuration-interaction (DFT/MRCI) approach. Structures, energies, and dipole moments are reported for all three states and compared to experimental values. From the optimized structures and calculated transition dipole moments, we predict that pure (1)L(b) bands will have positive signs for both the axis reorientation angle theta(T) and the angle theta of the transition dipole moment with respect to the inertial a axis. For (1)L(a) bands the signs of both angles will be reversed. Vibronically coupled bands can exhibit opposite signs for theta and theta(T). The absorption and emission spectra of indole are calculated based on the Franck-Condon Herzberg-Teller approximation using numerical transition dipole moment derivatives at the DFT/MRCI level of theory. Implications for the experimentally observed vibronic spectra are discussed. Predictions are made for rotationally resolved spectra of various rovibronic bands. A conical intersection, connecting the (1)L(b) and (1)L(a) states, which can be accessed to varying extents via different Herzberg-Teller active modes is found approximately 2000 cm(-1) above the (1)L(b) minimum.