ISSN:0005-9021    

DOI:10.1002/bbpc.198800050

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractIn this article we describe recent research of our group on the rate constants and the distribution of quantum states of the reaction products of unimolecular dissociations and on methods to treat intramolecular dynamics. Connections among various transition state type theories are also discussed.

ISSN:0005-9021    

DOI:10.1002/bbpc.198800052

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractA spatial correlation function has been previously proposed as a means of quantifying chaotic characteristics of quantum wavefunctions. In this paper we show that the classical analogue of the spatial correlation of a quantum wavefunction is identical (over short ranges) to its quantum counterpart, for the majority of high lying eigenstates of the classically chaotic stadium billiard problem. This behaviour is identified with quantumergodicity. Furthermore the classical correlation function is used to derive an energy‐scaling law for the correlation lengths. The spatial correlation approach is then generalized by considering cross‐correlation functions and the time evolution of the correlation lengths fornon‐stationaryquantum states. This quantity is shown to be a near constant of the motion for wavepackets comprised of chaotic states and may relate tomixingproperties of the dyn

ISSN:0005-9021    

DOI:10.1002/bbpc.198800053

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractBasic ideas and methods of the statistical analysis of energy spectra are reviewed. Complex nuclear, atomic and molecular spectra show typical fluctuation patterns which can be modeled with the aid of random matrices. Calculations on model systems and theoretical results show the existence of two universality classes of spectral fluctuations which depend on whether there are strong or only weak couplings between the various degrees of freedom. This correspondence also provides a link between quantum spectral statistics and classical dynamics. We illustrate statistical methods by analyzing model spectra obtained from a Hamiltonian which describes non‐Born‐Oppenheimer coupling of nuclear and electronic motion in molecu

ISSN:0005-9021    

DOI:10.1002/bbpc.198800054

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractRate constants for molecules excited to well defined states can vary, in an erratic fashion, over even narrow energy intervals. The theory of such fluctuations is discussed with special reference to the transition from regular to chaotic motion. It is argued that the distribution of the fluctuations with respect to the local average rate constantk(E) is that known as “chi square withvdegrees of freedom”. In particular, the width of the fluctuations is (2/v)1/2k (E). In the statistical limit the parametervequals the number of channels (≡ number of decay modes) accessible to an energy rich molecule in a given state. In this limit the distribution of fluctuations is universal and is independent of the dynamics. In general,v

ISSN:0005-9021    

DOI:10.1002/bbpc.198800055

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractSome properties of classical mechanical phase space resonances that serve as bottlenecks to the redistribution of internal molecular energy are investigated. Resonances of a two degree of freedom model van der Waals (vdW) molecule are subjected to a linear harmonic perturbation from an additional degree of freedom. The resulting effects on the phase portrait of the subsystem appear to be independent of the frequency of the third oscillator but relatively small coupling critically affects most quasi‐periodic resonances. The approximate separatrix in the vdW degree of freedom is used as a dividing surface in an analysis of the vdW molecule fragmentation rate. The influence on the separatrix of coupling to a third oscillator supports the validity of the two degree of freedom model for systems with small to moderate coupling. The golden mean resonance remains the most robust resonance of the two degree of freedom phase portrait even when the third oscillator coupling is nonzero, an observation which supports the recognition of golden mean resonances as the main intramolecular bottleneck

ISSN:0005-9021    

DOI:10.1002/bbpc.198800056

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractThe classical phase space dynamics of a simple two degree of freedom model for the vibrational predissociation (i.e. fragmentation) of van der Waals complexes is reviewed, with emphasis being placed on the role of transitions across intramolecular and intermolecular bottlenecks. A similar phase space picture is proposed to exist in van der Waals systems with three or more degrees of freedom. Evidence for this is presented with a 3D classical trajectory study of NeCl2fragmentation. An approximate intermolecular bottleneck is explicitly constructed for this system.

ISSN:0005-9021    

DOI:10.1002/bbpc.198800057

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractOne‐parameter fit versions of unimolecular rate theory for complex elimination and simple bond fission reactions are compared with detailed experiments. The agreement generally is so good that no further extension of this operational version of the theory is required. However, the relation between the fit parameter and properties of the potential surface not always is transparent. The article discusses the implementation of ab initio calculations of the potential by constructing adiabatic channel potential curves. Explicit results for charge‐dipole interactions are presented. SACM‐modified PST applies for selected conditions. Strategies for handling more complex potentials are outlined. The treatment closes the gap between operational fit parameters and potential prope

ISSN:0005-9021    

DOI:10.1002/bbpc.198800058

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractThe absorption and fluorescence characteristics of p‐difluorobenzene‐Ar van der Waals complexes prove ideally suited for experimental study of vibrational predissociation (VP). The process has been observed from seven S1complex levels that contain a total of six different ring modes. The levels have vibrational energies ranging between 240 and 900 cm−1. VP lifetimes are in the range of 2 – 12 ns for six of the levels. The other has a 200 ns lifetime, possibly because of relatively poor coupling of its hydrogenic bending motion with the dissociation coordinate. VP almost always occurs with only one or two major channels. The only exception is a level using three important channels. Remarkably, the final states of the VP are always the same, either 00or 61of the monomer. A strong Δv= 1 or 2 propensity rule for ring mode changes governs these VPs. The VP channels cannot be modelled well with the full collision state‐to‐state propensity rules known for Ar collisions. Difficulties are also encountered in modelling with a Golden Rule momentum gap formulation that has been successful in o

ISSN:0005-9021    

DOI:10.1002/bbpc.198800059

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY

摘要:

AbstractThe various mechanisms promoting predissociation in polyatomic molecules are reviewed, and illustrated by the spectroscopy of various electronic states of HNO, DNO, NH3and ND3. The quantum number dependences of the predissociation rates are used to discuss the particular mechanism(s) operating in each case. Recent observations using H‐atom time‐of‐flight spectroscopy of the energy disposal in the photodissociation of NH, through its à state show that a conical intersection in the exit channel has a massive influence on the dissociation dy

ISSN:0005-9021    

DOI:10.1002/bbpc.198800060

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1988

数据来源: WILEY