Molecular Relaxation in Liquids

331 Pages·2012·1.224 MB·English

by  Bagchi B.

Molecular Relaxation in Liquids
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Molecular Relaxation
in Liquids
B B
IMAN AGCHI
3
3
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LibraryofCongressCataloging-in-PublicationData
Bagchi,B.(Biman)
Molecularrelaxationinliquids/BimanBagchi.
p.cm. Includesbibliographicalreferencesandindex.
ISBN978-0-19-986332-7(hardcover:alk.paper)1. Relaxationphenomena.
2. Liquids. I. Title.
QD543.B1182012
538’.3–dc23 2011031643
1 3 5 7 9 8 6 4 2
PrintedintheUnitedStatesofAmerica
onacid-freepaper
Dedicatedtothelovingmemoryofmywife,SuhritaBagchi.
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CONTENTS
Preface xiii
Acknowledgments xv
Foreword xvii
1 BasicConcepts 3
1.1 Introduction 3
1.2 ResponseFunctionsandFluctuations 4
1.3 Time-CorrelationFunctions 6
1.4 LinearResponseTheory 6
1.5 Fluctuation-DissipationTheorem 8
1.6 Diffusion,Friction,andViscosity 8
1.7 Summary 10
2 PhenomenologicalDescriptionofRelaxationinLiquids 12
2.1 Introduction 12
2.2 LangevinEquation 13
2.3 Fokker–PlanckEquation 14
2.4 SmoluchowskiEquation 15
2.5 MasterEquations 16
2.6 TheSpecialCaseofHarmonicPotential 16
2.7 Summary 17
3 DensityandMomentumRelaxationinLiquids 19
3.1 Introduction 19
3.2 HydrodynamicsatLargeLengthScales 20
3.2.1 Rayleigh–BrillouinSpectrum 22
3.3 HydrodynamicRelationsbetweenSelf-DiffusionCoefficient
andViscosity 24
3.4 SlowDynamicsatLargeWaveNumbers:deGennesNarrowing 25
3.5 ExtendedHydrodynamics:DynamicsatIntermediateLengthScales 27
3.6 Mode-CouplingTheory 29
3.7 Summary 30
viii CONTENTS
4 RelationshipbetweenTheoryandExperiment 32
4.1 Introduction 32
4.2 DynamicLightScattering:ProbeofDensityFluctuationatLongLength
Scales 34
4.3 MagneticResonanceExperiments:ProbeofSingle-Particle
Dynamics 36
4.4 KerrRelaxation 38
4.5 DielectricRelaxation 38
4.6 FluorescenceDepolarization 39
4.7 SolvationDynamics(Time-DependentFluorescenceStokesShift) 40
4.8 NeutronScattering:CoherentandIncoherent 41
4.9 RamanLine-ShapeMeasurements 43
4.10 CoherentAnti-StokesRamanScattering(CARS) 45
4.11 EchoTechniques 45
4.12 UltrafastChemicalReactions 47
4.13 FluorescenceQuenching 47
4.14 Two-DimensionalInfrared(2D-IR)Spectroscopy 48
4.15 Single-MoleculeSpectroscopy 49
4.16 Summary 49
5 OrientationalandDielectricRelaxation 51
5.1 Introduction 51
5.2 EquilibriumandTime-DependentOrientationalCorrelation
Functions 55
5.3 RelationshipwithExperimentalObservables 57
5.4 MolecularHydrodynamicDescriptionofOrientationalMotion 57
5.4.1 TheEquationsofMotion 58
5.4.2 LimitingSituations 59
5.5 MarkovianTheoryofCollectiveOrientationalRelaxation:Berne
Treatment 59
5.5.1 GeneralizedSmoluchowskiEquationDescription 60
5.5.2 SolutionbySphericalHarmonicExpansion 62
5.5.3 RelaxationofLongitudinalandTransverseComponents 64
5.5.4 MolecularTheoryofDielectricRelaxation 64
5.5.5 HiddenRoleofTranslationalMotioninOrientational
Relaxation 65
5.5.6 OrientationaldeGennesNarrowingatIntermediate
WaveNumbers 66
5.5.7 ReductiontotheContinuumLimit 67
5.6 MemoryEffectsinOrientationalRelaxation 68
5.7 RelationshipbetweenMacroscopicandMicroscopicOrientational
Relaxations 70
5.8 TheSpecialCaseofOrientationalRelaxationofWater 72
5.9 LatticeModelsofOrientationalRelaxation 74
5.10 NonassociatedLiquids 75
5.11 Summary 76
CONTENTS ix
6 SolvationDynamicsinDipolarLiquid 78
6.1 Introduction 78
6.2 PhysicalConceptsandMeasurement 79
6.2.1 MeasuringUltrafast,Sub-100fsDecay 83
6.3 PhenomenologicalTheories:Continuum-ModelDescriptions 86
6.3.1 HomogeneousDielectricModels 86
6.3.2 InhomogeneousDielectricModels 89
6.3.3 DynamicExchangeModel 91
6.4 ExperimentalResults:AChronologicalOverview 93
6.4.1 DiscoveryofMultiexponentialSolvationDynamics:
Phase-I(1980–1990) 93
6.4.2 DiscoveryofSubpicosecondUltrafastSolvationDynamics:
Phase-II(1990–2000) 94
6.4.3 SolvationDynamicsinComplexSystems:Phase-III(2000–) 95
6.5 MicroscopicTheories 97
6.5.1 MolecularHydrodynamicsDescription 97
6.5.2 PolarizationandDielectricRelaxationofPureLiquid 98
6.5.2.1 EffectsofTranslationalDiffusioninSolvation
Dynamics 98
6.6 SimpleIdealizedModels 100
6.6.1 OverdampedSolvation:BrownianDipolarLattice 101
6.6.2 UnderdampedSolvation:StockmayerLiquid 102
6.7 SolvationDynamicsinWater,Acetonitrile,andMethanolRevisited 102
6.7.1 TheSub-100fsUltrafastComponent:MicroscopicOrigin 104
6.8 EffectsofSolvationonChemicalProcessesintheSolutionPhase 106
6.8.1 LimitingIonicConductivityofElectrolyteSolutions:Controlofa
SlowPhenomenonbyUltrafastDynamics 107
6.8.2 EffectsofUltrafastSolvationinElectron-TransferReactions 107
6.8.3 NonequilibriumSolvationEffectsinChemicalReactions 107
6.8.3.1 StrongSolventForces 109
6.8.3.2 WeakSolventForces 110
6.9 SolvationDynamicsinSeveralRelatedSystems 111
6.9.1 SolvationinAqueousElectrolyteSolutions 111
6.9.2 DynamicsofElectronSolvation 111
6.9.3 SolvationDynamicsinSupercriticalFluids 112
6.9.4 NonpolarSolvationDynamics 112
6.10 ComputerSimulationStudies:SimpleandComplexSystems 113
6.10.1 AqueousMicelles 114
6.10.2 WaterPoolinReverseMicelles 114
6.10.3 ProteinHydrationLayer 114
6.10.4 DNAGrooveHydrationLayer 115
6.11 Summary 115
7 ActivatedBarrier-CrossingDynamicsinLiquids 117
7.1 Introduction 117
7.2 MicroscopicAspects 119