Analysis of （1, 2） （1, 3） and （2, 3） Bands in the c^3Ⅱu- b^3Ⅱg System of P2

We investigate the high resolution absorption spectroscopy of P2 radical, generated in ac glow discharge of PC13 buffered with helium, using optical heterodyne magnetic rotation enhanced concentration modulation spectroscopy in the visible region. The （1, 2）, （1, 3） and （2, 3） bands of c^3Ⅱu- b^3Ⅱg in the range 16620-17860cm^-1 are observed and their 3II2 3II2 subbands are rotationally analysed. A set of effective molecular constants for the Ω= 2 component of the states involved are determined.     

Structure and conformational analysis of CFC-113 by density functional theory calculations and FTIR spectroscopy

Altitude-resolved volume mixing ratio profiles of CFC-113 have recently become available on a global scale with the Atmospheric Chemistry Experiment (ACE) satellite mission. However, the accuracy of the retrieval is currently limited by the uncertainties on the spectroscopic parameters of CFC-113. This paper reports on the geometrical structure, harmonic frequencies and intensities in the mid-infrared region of the two conformers of CFC-113 and the evaluation of whether theoretical calculations reproduce measurements. The calculations are performed using density functional theory at the B3LYP/6-311+G(3df) level. The molecular geometry parameters, the enthalpy difference and the potential barrier between conformers are calculated. The harmonic frequency of the normal modes of vibration are presented and accurately compared to experimental data. Overtones and combination bands are assigned in the 1200-2500 cm⁻¹ region.     

Theoretical investigations of homo- and heteronuclear bridged fullerene oligomers

\chem{[C_{60}]_{\chemindex{n}}} -oligomers (, , and ) as well as dimers partially bridged by oxygen atoms or a group. The applicability of the scheme for finding the ground state of these systems was carefully checked against more sophisticated methods including an all-electron, self-consistent (SCF) scheme based on the local-density-approximation (LDA), and the recently developed generalized-gradient approximation (GGA). We present Raman intensities for the vibrations of the oligomers, obtained in the framework of the bond polarization model, and compare with recent experimental data. Received: 26 September 1996/Accepted: 16 December 1996     

Matching allele dynamics and coevolution in a minimal predator-prey replicator model

A minimal Lotka-Volterra type predator-prey model describing coevolutionary traits among entities with a strength of interaction influenced by a pair of haploid diallelic loci is studied with a deterministic time continuous model. We show a Hopf bifurcation governing the transition from evolutionary stasis to periodic Red Queen dynamics. If predator genotypes differ in their predation efficiency the more efficient genotype asymptotically achieves lower stationary concentrations.     

Torsional barriers and nonlinear optical properties of 2-, 3-, 4-phenylpyridine molecules

The torsional barriers and nonlinear optical properties for all phenylpyridine molecules were calculated by using Hartree-Fock (HF) theory and Becke three-parameter functional (B3LYP) hybrid approaches within the density functional theory framework with the 6-31++G(d, p) basis set, and via the GAUSSIAN 98W. The torsional barrier computations show that dihedral angle between the two rings increases with the number of H-H vicinal interactions and torsional barriers with dihedral angles for 3-, 4-phenylpyridines are too similar for both HF and B3LYP level calculations. Also, HOMO-LUMO energy gaps, polarizabilities, anisotropy of polarizabilities, and static hyperpolarizabilities are calculated as a function of dihedral angle between benzene and pyridine rings. The study reveals that the phenylpyridines show very low nonlinear optical properties. The calculated torsional barrier, equilibrium dihedral angle and molecular dipole moment results for these molecules were compared with available experimental and other results determining from different computational methods.     

Cavity ring-down spectroscopy of H2O in the range 16 570-17 125 cm

Following previous investigations on H₂¹⁶O and H₂¹⁸O by cavity ring-down spectroscopy, this method has now been applied to investigate the energy region of the 5ν polyad in the absorption spectrum of H₂¹⁷O. In the range 16 570-17 125 cm⁻¹, the highest energy range investigated for the H₂¹⁷O isotopologue so far, 516 lines are attributed to H₂¹⁷O and assigned from a newly generated line list.     

Highly localized vibronic wavepackets in large reactive molecules

The ultrafast dynamics of the internal conversion of S₁ azulene and the excited-state intramolecular proton transfer in 2-(2^′-hydroxyphenyl)benzothiazole (HBT) were investigated by pump–probe spectroscopy with tunable pulses as short as 20 fs. In both cases we find very pronounced oscillatory contributions to the transients, which are due to vibrational wavepacket motion in the excited state. The damping times are on the order of 1 ps even for these large reactive molecules in solution at room temperature. For azulene only 2 out of 48 vibrational modes participate and in HBT only 4 out of 69. This high degree of localization of the wavepacket seems to be a general feature, and supports hopes that even for systems of chemical interest coherent control might be possible. Received: 24 January 2000 / Published online: 24 July 2000     

Quantum nonintegrability and the classical limit for usp(4) systems

We investigate the transition from integrability to chaos in a system built of usp(4) elements, both in the quantum case and in its classical limit, obtained using coherent states. This algebraic Hamiltonian consists in an integrable term plus a nonlinear perturbation, and we see that the level spacing distribution for the quantum system is well approximated by the Berry-Robnik-Brody distribution, and accordingly the classical limit displays mixed dynamics.     

Iodine hyperfine structure and absolute frequency measurements at 565, 576, and 585 nm

The hyperfine structure splittings of the P(10)14-1, R(15)14-1, and R(99)15-1 transitions at 585 nm, P(62)17-1 at 576 nm, and P(80)21-1 at 565 nm in ¹²⁷I₂ are measured by heterodyne spectroscopy using two dye lasers. In addition, the absolute frequencies of the hyperfine components P(10)14-1 a₁₅ and P(80)21-1 a₁₀ are determined using a self-referenced frequency comb. These frequencies are used in an experiment testing relativistic time dilation by laser spectroscopy on a fast ion beam.     

Light-driven molecular switches and motors

Technology is omnipresent in our modern-day society and it is hard to imagine a world without machines, computers or robots. One of the main current scientific challenges is the bottom-up construction of systems that represent nanosize analogues of switches, devices and motors. Our efforts in this area have focussed on the construction of devices based on sterically overcrowded alkenes. In this paper, we present our ongoing research on the construction of binary molecular switches, which has recently led to genuine molecular motors. The control of chirality in a molecular switching system allows interconversion between molecules of opposite helicity using different wavelengths of light. Such bistable chiral switches are of potential use in optical data storage and processing at the molecular level. The control of molecular chirality is even more subtle in the case of molecular motor systems. The exquisite control of chirality using light as an energy source has resulted in a controlled, repetitive 360° unidirectional rotation in two generations of molecular motor systems. Received: 21 January 2002 / Accepted: 11 February 2002 / Published online: 22 April 2002     

Creating, detecting and locating ultracold molecules in a surface trap

Ultracold molecules have been produced by photoassociation of Cs atoms trapped in a mirror magneto-optical trap. The molecules were detected by resonantly enhanced multi-photon ionization followed by time-of-flight mass spectroscopy. The time-of-flight ofatomic and molecular ions was investigated in the presence of a dc bias voltageapplied to the conducting mirror. This technique provides a new tool for determining the distance between the cold molecules and the mirror surface. This revised version was published online in August 2005 with a corrected cover date.     

Rescattering and vibrations in homonuclear diatomic molecules in a strong electromagnetic field

The electron of a driven by a strong electromagnetic field induces molecular vibrations. Numerical and analytical results show that the molecule behaves as a parametric oscillator and can be treated as a kicked oscillator. The results are discussed from the point of view of the electron's periodic dressing and undressing processes.     

Bipartite Entanglement in the Two-Mode Quantum Kicked Top

We show that the bipartite entanglement in the two-mode quantum kicked top can reveal the underlying chaotic and regular structures in phase space： namely, the entanglement displays a rapid rise after a very short time for an initial spin coherent state centred in a chaotic region of the phase space, whereas the entanglement displays a periodic modulation for the coherent state centred at an elliptic fixed point. The quantum-classical correspondence is investigated by studying the mean and maximal linear entropy.     

Dynamics Analysis and Transition Mechanism of Bursting Calcium Oscillations in Non-Excitable Cells

A one-pool model with Ca^2＋-activated inositol-trisphosphate-concentration degradation is considered. For complex bursting Ca^2＋ oscillation, point-cycle bursting of subHopf-subHopf type is found to be in the intermediate state from quasi-periodic bursting to point-point bursting of subHopf-subHopf type. The fast-slow burster analysis is used to study the transition mechanisms among simple periodic oscillation, quasi-periodic bursting, point-point and point-cycle burstings. The dynamics analysis of different oscillations provides better insight into the generation and transition mechanisms of complex intra- and inter-cellular Ca^2＋ signalling.     

Improved molecular constants for the and states of NaH

Improved molecular constants for the and states of the NaH molecule are presented. NaH molecules are produced by reactive scattering of H and Na₂ in a crossed beam experiment. High vibrational levels (6 9) of the NaH molecules are predominantly populated. Their excitation spectrum in the range has been measured using a new variant of Doppler spectroscopy. The transition frequencies involving the vibrational levels 2 8 in the and 6 9 in the state have been determined with an accuracy of better than . Using also previously published data a new set of molecular constants for the and state is derived. In particular, the vibrational dependence of the rotational constants B, D and H as well as some of v”-v' band origins for and is determined. The transition frequencies measured here or published previously are reproduced by these new coefficients with an accuracy of 0.1 cm^-1 [rms value] with a maximum deviation of 0.4 cm^-1. New RKR potential energy curves have been calculated up to the turning points of the levels v” = 9 in the state and v' = 25 in the state. Received 21 August 1999     

Bursting Ca2+ Oscillations and Synchronization in Coupled Cells

A mathematical model proposed by Grubelnk et al. [Biophys. Chem. 94 （2001） 59] is employed to study the physiological role of mitochondria and the cytosolic proteins in generating complex Ca^2＋ oscillations, lntracellulax bursting calcium oscillations of point-point, point-cycle and two-folded limit cycle types are observed and explanations are given based on the fast/slow dynamical analysis, especially for point-cycle and two-folded limit cycle types, which have not been reported before. Furthermore, synchronization of coupled bursters of Ca^2＋ oscillations via gap junctions and the effect of bursting types on synchronization of coupled cells are studied. It is argued that bursting oscillations of point-point type may be superior to achieve synchronization than that of point cycle type.     

Algebraic methods in quantum mechanics: from molecules to polymers

We present a brief review of algebraic techniques developed and applied in molecular spectroscopy in the last five years. We also outline perspectives for new applications of the Lie algebraic method in the first decade of the new century. Received 21 November 2001     

Planar imaging of a laboratory flame and of internal combustion in an automobile engine using UV rayleigh and fluorescence light

Rayleigh scattering of tunable excimer laser light (193 nm and 248 nm) is used to obtain 2-D images of the distribution of total densities in a laboratory flame and in a cylinder of an automobile engine. Because the UV light is very strongly scattered, there is ample signal and there is excellent contrast of Rayleigh light against surface scattered light, even in the small volume of the engine cylinder. The laboratory flame data are converted to an image of the temperature field. The Rayleigh images are compared with those from planar laser induced predissociative fluorescence, which yield state-specific densities of selected molecules. The experimental arrangement is the same except for the selection of laser wavelength and the filtering of the radiated light.