Low-frequency vibrations specific for conformers of 1-aminoindan studied by UV-UV hole-burning spectroscopy

The UV-UV hole-burning spectra of the jet-cooled 1-aminoindan were measured for the first time. Complicated spectral features observed in the laser-induced fluorescence excitation spectrum due to two conformers, R and B, were firmly separated. On the basis of fluorescence measurements and B3LYP/cc-pVTZ calculations, low-frequency ring twisting and ring puckering modes were assigned. These modes are coupled in the S1 state due to the Duschinsky rotation. The Duschinsky matrix was calculated from the normal modes predicted by quantum chemical calculations. The coupling between the twisting and puckering modes for conformer B is stronger than that for conformer R. The twisting mode was observed at 0+99 cm(-1) in the S1 state for conformer B, while not for conformer R. The Franck-Condon activity of the twisting mode substantially differs between the two conformers. The transition to the twisting level for conformer B would be allowed by the Duschinsky rotation. The fluorescence lifetime of conformer vibronic levels was also measured and differed for each conformer.     

Intermolecular potential energy surface of Ar-NO

Rotational spectra of an open-shell complex, Ar-NO, in the electronic ground state have been analyzed by employing an analysis using a free-rotor model, where previously observed data by Mills et al. [J. Phys. Chem. 90, 3331 (1986); 90, 4961 (1986)] and additional transitions observed by Fourier-transform microwave spectroscopy in the present study are simultaneously analyzed with a standard deviation of the least-squares fit to be 27.5 kHz. A two-dimensional intermolecular potential energy surface for Ar-NO has been determined from the analysis. The determined potential energy surface is compared with those of Ar-OH and Ar-SH, which are also complexes containing an open-shell species with the 2Pi ground electronic state.     

Monitoring the effect of a control pulse on a conical intersection by time-resolved photoelectron spectroscopy

We have previously shown how femtosecond angle- and energy-resolved photoelectron spectroscopy can be used to monitor quantum wavepacket bifurcation at an avoided crossing or conical intersection and also how a symmetry-allowed conical intersection can be effectively morphed into an avoided crossing by photo-induced symmetry breaking. The latter result suggests that varying the parameters of a laser to modify a conical intersection might control the rate of passage of wavepackets through such regions, providing a gating process for different chemical products. In this paper, we show with full quantum mechanical calculations that such optical control of conical intersections can actually be monitored in real time with femtosecond angle- and energy-resolved photoelectron spectroscopy. In turn, this suggests that one can optimally control the gating process at a conical intersection by monitoring the photoelectron velocity map images, which should provide far more efficient and rapid optimal control than measuring the ratio of products. To demonstrate the sensitivity of time-resolved photoelectron spectra for detecting the consequences of such optical control, as well as for monitoring how the wavepacket bifurcation is affected by the control, we report results for quantum wavepackets going through the region of the symmetry-allowed conical intersection between the first two (2)A' states of NO(2) that is transformed to an avoided crossing. Geometry- and energy-dependent photoionization matrix elements are explicitly incorporated in these studies. Time-resolved photoelectron angular distributions and photoelectron images are seen to systematically reflect the effects of the control pulse.     

Electronic spectra of the jet-cooled 1-methylvinylthio radical

Electronic spectra of the B?-X? transition of the 1-methylvinylthio radical were observed in a discharged jet of propylene sulfide by laser-induced fluorescence spectroscopy. Identification of the spectral carrier was made by comparing the observed spectra with results of molecular orbital calculations, in particular, for vibrational frequencies, rotational contour simulations, and the Franck-Condon simulations. Vibrational structures observed in the electronic spectra indicate that the 1-methylvinylthio radical can be regarded as a molecule with C(s) symmetry at the zero-point levels of both the excited and ground states.     

Metal array fabrication through self-assembly of Pt-complex-bound amino acids

A new type of Pt-complex-bound amino acid was synthesized by condensation of a cyclometalated Pt complex with the side-chain residue of N- and C-alkylated glutamic acid. Self-assembly of the Pt-bound lipophilic amino acid afforded a supramolecular gel in organic solvents, which comprised fibrous lamellar aggregates that supported a highly oriented Pt array.     

57Fe M?ssbauer analysis of the Upper Triassic-Lower Jurassic deep-sea chert: Paleo-redox history across the Triassic-Jurassic boundary and the Toarcian oceanic anoxic event

We investigated the paleo-redox change across the Triassic-Jurassic (T-J) boundary (～200?Ma) and the Early Toarcian oceanic anoxic event (T-OAE; ～183?Ma) recorded in the Upper Triassic to Lower Jurassic pelagic deep-sea cherts in the Inuyama area, Central Japan. The present ⁵⁷Fe M?ssbauer spectroscopic analysis for these cherts identified five iron species, i.e., hematite (α-Fe₂O₃), pyrite (FeS₂), paramagnetic Fe^3?+?, and two paramagnetic Fe^2?+? with different quadrupole splittings. The occurrence of hematite and pyrite in deep-sea cherts essentially indicates primary oxidizing and reducing depositional conditions, respectively. The results confirmed that oxidizing conditions persisted in deep-sea across the T-J boundary. In contrast, across the T-OAE, deep-sea environment shifted to reducing conditions. The first appearance of the gray pyrite-bearing chert marked the onset of the deep-sea oxygen-depletion in the middle Pliensbachian, i.e., clearly before the shallow-sea T-OAE.     

On the Wave Operators for the Friedrichs–Faddeev Model

We provide new formulae for the wave operators in the context of the Friedrichs–Faddeev model. Continuity with respect to the energy of the scattering matrix and a few results on eigenfunctions corresponding to embedded eigenvalues are also derived.