Ab initio electronic structure calculations for phenol and the hydrogen-bonded complexes phenol · H₂O and d-phenol · D₂O were performed at the Hartree-Fock 4-31G and 6-31G^** levels. Both phenol and phenol · H₂O were fully structure optimized. Based on the minimumenergy structures so obtained, full normal coordinate analyses were carried out. The resulting harmonic frequencies were scaled and compared to available experimental data. The agreement is satisfactory and allows for an assignment of a majority of the bands observed in the experimental spectra. Comparison with previous calculations on (H₂O)₂ reveals a considerable increase in the strength of the hydrogen bond on going from (H₂O)₂ to phenol · H₂O.

We report on crystal growth and about physico-chemical studies on Sr_yBa_1−yFCl_xBr_1−x (y = 0, 0.5, and 1) compounds doped with Sm. Persistent spectral hole burning at 300 K is further reported on Sr_0.5Ba_0.5FCl_0.5Br_0.5:Sm single crystals.

The high-spin to low-spin (HS→LS) relaxation in the [Fe(ptz)6](BF4)2 spin-crossover system deviates strongly from first-order kinetics because of cooperative effects of elastic origin. The shift in horizontal and vertical displacement of the potential wells of the initial and final state relative to each other due to the build-up of an "internal" pressure is estimated from spectroscopic measurements. The HS→LS relaxation as such is described by the theory of nonadiabatic multiphonon relaxation in the strong-coupling limit, with a Huang—Rhys factor S ≈ 45 which is much larger than the reduced energy gap p. The sigmoidal relaxation curves in [Fe(ptz)6](BF4)2 result when a change in S of ≈ −1 and in p of 1 during the relaxation is taken into account.

The constructive interference between two Stark-effect-broadened holograms produced by spectral hole burning is discussed. The holograms are burned at the same frequency but at different external electric-field values. The phase difference is selected to be zero so that constructive interference between the waves diffracted by each grating occurs. Experimentally it is found that a dip in the hologram efficiency that is not predicted by previous theory occurs for all reconstruction external electric-field values in the region between the original burn values. This dip is interpreted as being due to the time nonlinearity of the hologram burn process. The dip corresponds to those molecules, oriented in a specific direction with respect to the electric field, for which no Stark shift occurs and that are therefore resonant with the laser during the production of both holograms. The width of the anomalous feature is close to that of the hologram when the hologram is reconstructed at the original burn external electric-field strength. Other molecular orientations may be selected by burning pairs of holographic gratings at other combinations of the frequency and the electric field.

The electron transfer reaction between 9,lO-anthraquinone (AQ) excited to the lower triplet state and 1,2,4trimethoxybenzene (TMB) in solvents of different polarity has been studied by nanosecond time-resolved resonance Raman spectroscopy. In no solvent was there evidence for the formation of a triplet exciplex. All the observed vibrations were characterized as AQ* or TMB" modes. The frequency of the band assigned to the C-C stretch of TMB" has been found to be very dependent upon the environment and this effect has been used to observe the separation of the geminate ion pair into free ions in polar solvents. The data strongly suggest that the ions are at van der Waals contact in the geminate ion pair and not separated by solvent molecules.

A series of [Cr(benzene)(CO)2L] complexes with L = PPh3, P(OMe)3, PPh2 ((−)-menthyl), P(OPh)2(O-(−)-menthyl), P(O-(−)-menthyl)3 were subjected to a nueleophile addition/acylation sequence to give trans-5,6-disubstituted cyelohexadienes. Low-to-moderate asymmetric induction was observed with the chira] ligands. Experimental and theoretical evidence for an alkylation at the metal center trans to the P ligand is presented, and a crystal structure determination of a [Cr(η5-cyclohexadienyl)(P(OMe)3)(CO)2SnPh3] complex is included.