79466 - Spectroscopy of Condensed Phases

Learning outcomes

The course aims at providing the student with the theoretical fundamentals for understanding, analyzing and predicting spectroscopic observables in fluid condensed phases (liquids, liquid crystals, polymers, membranes and other soft materials). The molecular description of static observables and dynamic processes (evolution equations, correlation functions , linear response theory, stochastic processes, diffusion etc..) will be presented with applications to various kind of spectroscopies: absorption, fluorescence depolarization, dielectric relaxation, NMR, X ray and neutron scattering. The prediction of observables from molecular dynamics computer simulations will also be discussed.

Course contents

The course deals with the following topics:

Introduction to the molecular description of structure and dynamics of fluid condensed phases (liquids, liquid crystals, micelles and membranes, glasses, selected polymers).

Static observables. One and two particle static distribution functions. Expansion of the distributions in an orthogonal basis set. Order parameters and their physical significance. Radial distributions and structure factors.

X-ray scattering as a way of obtaining structural information for various condensed phases.

Time dependent observables. Correlation functions and their physical significance. Stochastic processes for molecular evolution: rotational diffusion and strong collision limits. Relaxation times. Fourier transforms and spectral densities.

Interaction radiation-matter. Polarized radiation. Absorption and emission. Transition probability and transition dipole moments. Spectroscopical lineshapes and time correlation functions. Link to Infrared and Raman spectroscopies.

Fluorescence and its polarization decay as a tool to study order and molecular dynamics. Examples of application for fluorescent probes in liquid crystals and membranes

Linear Response theory. Dynamic properties through frequency response. Examples: frequency dependent conductivity and dielectric response, magnetic resonance and relevant correlation functions.

Dielectric Relaxation Spectroscopy. Real and imaginary components of the dielectric susceptivity and their relation with molecular structure. Dipolar orientational correlation functions. Cole-Cole plots. Applications.

The Molecular Dynamics (MD) technique as a way to predict or interpret spectroscopic observables. Introduction, practical implementation, applications.

Readings/Bibliography

A printed copy of the slides and of other documents if needed will be made available to the students before each group of lectures. These notes will be sufficient to prepare the final exam. For further reading:

C. Wang, Spectroscopy of Condensed Media. Dynamics of Molecular Interactions (Academic Press, Orlando, 1985)

ISBN 0-12-734780-1

C. Zannoni, Liquid crystal observables. Static and dynamic properties. in Advances in the Computer Simulations of Liquid Crystals, edited by P. Pasini and C. Zannoni (Kluwer, Dordrecht, 2000), p. 17-50

C. Zannoni, The Molecular Dynamics Method: An Introduction. in The WSPC Reference on Organic Electronics: Organic Semiconductors, edited by S. M. J.-L. Bredas, 2016), Vol. 1, p. 53

Teaching methods

The course is based on a series of front lectures

Assessment methods

The reaching of the teaching aims of the course will be assessed with an oral examination on the topics covered during the lectures

Teaching tools

Powerpoint slides

Blackboard

Office hours

See the website of Claudio Zannoni