Ab initio multi-reference configuration interaction of the low-lying states of the AsP molecule

Nine low-lying electronic states of the AsP molecule, including Σ , Ⅱ, and △ symmetries with singlet, triplet, and quintet spin multiplicities, are studied using multi-reference configuration interaction method.The potential energy curves and the spectroscopic constants of these nine states are determined, and compared with the experimental observed data as well as other theoretical works available at present.Three quintet states are reported for the first time.Furthermore, the analytical potential energy functions of these states are fitted using Murrell-Sorbie function and least square fitting method.     

Optical system and lens design for Blu-ray disc optical pick-up

During the design process of Blu-ray disc optical pick-up (BD OPU), the optical system and the collimator lens design is especially important. This paper designs an optical system and some lenses for the BD OPU, including collimator lens, beam shaping lens for laser beam shaping, and cylinder lens for signal detecting. In this OPU, we use a triplet lens to collimate the laser beam. At the same time, we build a series of assembly jigs to make sure that each lens can be put into the OPU basement properly. At last, we get the reading spot image and S-curve photo of OPU, which can be used to read Blu-ray disc (BD).     

Photoisomerization of norbornadiene group in a rigid bichromophoric compound initiated by remote keto chromophore: long-distance through-bond triplet energy transfer

A diad compound 3β(bicyclo[2,2,1]hepta-2,5-diene-2-methylcarboxylate-3-carboxy)-an-drost-5-en-17-one (NBD-S-ONE) was synthesized and its photochemistry was examined. Irradiation of NBD-S-ONE in acetonitrile at λ > 300 nm selectively excited the keto chromophore. After intersystem crossing, the triplet energy of the keto group was transferred to the NBD group with 18.6% efficiency via a through-bond mechanism, resulting in the isomerization of the latter group to the quadricyclane group.     

Magnetostatic modulation of nonlinear refractive index and absorption in quantum wires

The magnetic-field dependence of the nonlinear differential refractive index Δnand absorption Δα in quantum wires—measured by non-degenerate pump and probe spectroscopy—is investigated theoretically. The nonlinearities arise from population saturation of the excitonic state under optical pumping and the formation of biexcitons (excitonic molecules). Both Δnand Δ α exhibit positive and negative peaks at certain pump and probe detuning frequencies associated with the formation of biexcitons and bleaching of excitons, respectively. The amplitude, lineshape and the frequency at which these peaks occur can be modulated by a magnetic field which opens up the possibility of realizing novel magneto-optical devices. Additionally, the magnetic field may allow us to realize a relatively large variation in the differential refractive index over a range of frequencies without significant accompanying absorption, thereby allowing the observation of optical bistability.     

Heteroannihilation of the excited states of associates and monomers of fluorescein dyes on the silica surface at low temperatures

The processes of homo-and hetero-triplet—triplet annihilation (TTA) of Bengali rose on the spongy silicon surface have been investigated. It has been found that upon pulse photoexcitation on the silica surface photophysical processes involving the triplet states of monomers and their associates can develop. It has been shown that the processes of hetero-TTA are inhibited due to the decomposition of associates under the influence of hexane molecules in the molecular clusters of the dye adsorbates. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 734–737, November–December, 2005.     

Intermolecular Vibrational Relaxation in Mixtures of Excited Benzophenone and Anthraquinone Molecules with Water Vapor

The intermolecular vibrational energy transfer from triplet molecules of benzophenone and anthraquinone to H₂O molecules has been investigated. To determine the rates of establishment of vibrational (V-V) and thermal (V-T) equilibrium in a vibrational quasi-continuum of mixed singlet-triplet levels, the dependences of the decay rates and intensities of the fast and slow components of delayed fluorescence on the H₂O vapor pressure have been investigated. For V-V relaxation, the efficiencies ₁ and the mean energies E transferred per collision in mixtures with H₂O and other polyatomic foreign gases have been compared. It has been established that the efficiencies ₁ for quasi-resonant vibrational energy transfer (V-V) from benzophenone and anthraquinone to H₂O are an order of magnitude lower than the gas-kinetic ones and lower than those obtained under the same experimental conditions for such foreign gases as C₅H₁₂, SF₆, and CCl₄, and decrease with increasing temperature in the 433–513 K range. It has been concluded that the mechanism of V-V relaxation in mixtures with H₂O are determined by long-range attractive forces. In mixtures with H₂O, no acceleration of V-T relaxation due to the formation of hydrogen bonds has been revealed. The low-efficiency thermalization process (V-T relaxation) is controlled by short-range repulsive forces, and the differences between the intensities ₂ for mixtures of benzophenone and anthraquinone with H₂O and other polyatomic gases are determined by the change in the reduced mass of interacting molecules.     

Time resolve study on isopropyl-ether porphyrindiol

In the past years extensive studies have been conducted on porphyrin-type photosensitizers because of their photosensitive activity. With regard to their interaction with many important macromolecules such as nucleic acids, proteins and lipids, porphyrin-type photosensitizers are capable of damaging numerous cells. They damage DNA via oxidation of four bases, especially guanine and cytosine pairs[1], damage protein by oxidation of (at least) two amino acids——cysteine and tryptophan residues…     

Chemiluminecsence in the oxidation of Na2C60 by the (NH4)2Ce(NO3)6 complex in THF

Chemiluminescence (_max = 790 nm) in the oxidation of fulleride Na₂C₆₀ by the (NH₄)₂Ce(NO₃)₆ complex in THF was found. The ³C₆₀* triplet of fullerene formed in the transfer of an electron from the intermediate C₆₀ ^– anion to Ce^IV was suggested to be the chemiluminescence emitter.     

Polaronic shift of the Wannier-Mott exciton binding energy in a quantum wire with allowance for the phonon confinement effect

Within the framework of the Li-Low-Pines model the interaction of a Wannier-Mott exciton with polar optical phonons in a cylindrical semiconductor wire is studied, taking into account the phonon confinement effect. An analytical expression for the exciton binding energy with allowance for the polaronic effect is obtained. Numerical calculations of the binding energy are carried out for AlAs/GaAs/AlAs and ZnSe/CdSe/ZnSe wires with a various degree of polarity of quantum wire materials. The polaronic shift of the binding energy of light and heavy hole excitons is calculated.     

Energy spectra of exciton states in disk-shaped GaAs-Ga<Subscript>1-x</Subscript>Al<Subscript>x</Subscript>As quantum dots under growth-direction magnetic fields

A theoretical study, within the effective-mass approximation, of the effects of applied magnetic fields on excitons in disk-shaped GaAs-Ga_1-xAl_xAs quantum dots is presented. Magnetic fields are applied in the growth direction of the semiconductor heterostructure. The parity of the excitonic envelope function related to the simultaneous exchange of z_e→-z_e and z_h→-z_h is a good quantum number and the wave function, both the odd and even parity, can be expanded as combination of products of the quantum well electron and hole function that preserves the parity with appropriate Gaussian functions. We have simultaneously obtained the energies of the excitonic ground and excited states and discuss the behavior of these energies as a function of the magnetic field.