Frontiers in Spectroscopy

Chemical Physics 880 (20169-9) and 880A (20170-7)

Winter 2004

Course Description: This course will provide students with an overview of topics on the frontier of spectroscopic research. It will exploit internationally renowned lecturers, as well as outstanding OSU faculty, to cover topics ranging from very fundamental to quite applied. General areas to be covered will include fundamental characteristics of molecular quantum structure, electromagnetics, new experimental techniques, remote sensing, ultra-high sensitivity analytical techniques, astrophysical applications, etc. It is planned that the course will be offered multiple times, with topics and speakers varying with each offering. The lecturers for the upcoming Winter quarter are listed below.

Each topic will be covered by lectures on Wednesday and Friday mornings, 9:00-10:18AM, in MP2015, with a discussion period 9:00-10:18AM on Thursdays in MP2015.

Prerequisites: Chemistry 866 or Physics 780.04 or permission of the instructor

Required Text: None; suggested articles for reading will be supplied prior to the lecture on a given topic.

Syllabus:

List of speakers and dates scheduled:

January 14-16 Mark Child, University of Oxford
Click here: 1 (view from Internet Explorer), 2, 3, 4 to access readings for these lectures. Click here for an abstract of the lectures.
Click here for Wednesday's powerpoint presentation. Click here for Friday's powerpoint presentation.

February 4-6 Rick Freeman, OSU. Readings: Fast Ignition paper 1, Fast Ignition paper 2

February 18-20 Peter Toennies, Max Planck Institute Click here for an abstract of the lectures.
Click here1, 2, 3 for links to his transparencies. (view from Internet Explorer)
LECTURE I Ref 1 Ref 2 HTML version PDF version Ref 3 Ref 4 LECTURE II Ref 1 Ref 4

February 25-27 Bob Field, MIT Click here1, 2 and 3 for links to his transparencies used during his lectures.

Lecture # 1. "The SEP and DF Spectra of Acetylene are Not Intrinsically Unassignable"
This lecture will be an introduction to Intramolecular Vibrational Redistribution. The Stimulated Emission Pumping and Dispersed Fluorescence spectra of acetylene will serve as an example to illustrate all concepts.

The potential energy surface of even a small polyatomic molecule is specified by an obscene number of cubic and quartic anharmonic constants, but only a small fraction of these are dynamically relevant. It is the difference between ordinary nondegenerate perturbation theory, where second-order corrections to the energy are sufficient, and quasi-degenerate perturbation theory, where a small matrix must be diagonalized. The key concept is "resonance". When two or more modes have frequencies in near integer ratios, their anharmonic interactions are resonant and must be treated by a "polyad" effective Hamiltonian. Polyads describe early time dynamics at all energies, even when normal modes become an extremely bad approximation. Polyads obey convenient matrix element scaling and selection rules.

The DF spectra of acetylene, recorded from several different vibrational levels of the electronically excited A(over tilde) ^1A_u state, can be unzipped into separate polyads, even though the polyads overlap. A statistical method for accomplishing this unzipping, extended spectral cross correlation (XCC), will be described. The polyads revealed by XCC are fitted to an effective Hamiltonian matrix, and this matrix generates surprising new classes of eigenstates: local benders and counter-rotators.

Readings for this lecture JPC 104, 3073 (2000), JCP 107, 8349 (1997), and Book, pp 683-690

Lecture # 2. "It's What You Pluck: A Tutorial on Intramolecular Dynamics"

The concepts and some of the visualization tools of intramolecular dynamics will be introduced and illustrated with examples from the Dispersed Fluorescence, Laser Induced Fluorescence, and Surface Electron Ejection by Laser Excited Metastables (SEELEM) spectra of acetylene. Although the same names are used to describe basis states and eigenstates, they are not remotely the same. One plucks basis states, which are not eigenstates, hence the wavefunction created at t=0 evolves in time. The concepts "bright state", "dark state", and "doorway" state are essential to an understanding of the difference between statistical and mechanistic dynamics. Doorways states and polyads are part of a "reduced dimension" picture of dynamics. An example of ergodic dynamics is illustrated by surprisingly regular, rotationally assignable SEELEM spectra of T_1 vibrational levels of acetylene.

The dissolution of doorway states in a dark state bath is explained with reference to the strong and weak coupling limits of an effective Hamiltonian with complex diagonal elements.

Reading for this lecture: Book, pp 622-624, 683-690, 671-682

Lecture #3 "From a Quantum Mechanical Effective Hamiltonian to a Classical Mechanical Hamiltonian: Views of Intramolecular Dynamics"

The polyad effective Hamiltonian will be expressed in terms of creation, annihilation, and number operators. These operators are convenient for transforming between normal and local mode basis sets and also between quantum and classical mechanical representations of intrapolyad dynamics. In the classical mechanical picture, surfaces of section provide insights into qualitative changes in the nature of the dynamics.

Each off diagonal coupling operator may be partitioned into two non-Hermitian terms, W and W^dagger. From these operators resonance and transfer rate operators are formed with which the dynamics of any initially prepared non-eigenstate may be visualized. The use of the resonance and transfer rate operators is illustrated using the DF spectrum of acetylene.

Reading for this lecture: JPC 104, 3073, (2000)., 2. JCP 111, 600 (1999) CPL 320, 553 (2000), and Book, pp 635-639, 646-649, 692-700, 702-733.

March 3-5 Paul Ewart, University of Oxford Readings 1, 2, 3, and 4 (reading 4 best seen through internet explorer)

Click here1, 2 and 3 for links to his powerpoint presentations used during his lectures.

Grading: Satisfactory/Unsatisfactory options: Class attendance and participation

Letter grade option: Class attendance and participation plus term paper

(Grades will be assigned solely by OSU faculty.)  

20169-9 (3 hours) Call number for ChemPhys 880 (S/U option)

20170-7 (3 hours) Call number for ChemPhys 880A (letter grade option - prerequisite=a previous spectroscopy course at OSU in Chemistry or Physics or prior permission of the instructor)