## CHEM2303: Chemical Dynamics

**Course Organizer: ** **Prof Helen Fielding**

**Lecturers: Dr Simon Banks, ****Prof Helen Fielding**** and Dr Giorgio Volpe**

Normal prerequisite: CHEM1301 / CHEM2301

Units: 1/2

Moodle page: http://moodle.ucl.ac.uk/course/view.php?id=1035

#### Aims

The aim of this course is to teach students the fundamentals of modern chemical dynamics and modern experimental methods in chemical physics.

#### Objectives

At the end of the course, students will be able to understand molecular potential energy surfaces, molecular collisions and light-matter interactions. The emphasis is on both developing an understanding of the underlying chemical physics principles and on learning about state-of-the-art experimental techniques.

#### Course Structure

- Lectures: 27 (including worked problems)
- Workshops: 3
- Labs:0

#### Assessment

- Exam: 80% (2 hours)
- Lab: 0%
- Coursework: 20%

#### Recommended Texts

**Photophysics and
Photochemistry (STB)**

These lectures do not follow one specific text book or primer; however, the following books have all been used as source material and you may find some of them useful.

*Photochemistry* - C. E. Wayne and R. P. Wayne (Oxford Chemistry
Primer)
Principles of Molecular Photochemistry (An
Introduction) - J. Turro, V. Ramamurthy
and J. C. Scaiano.
Molecular quantum mechanics - Atkins and Friedman

**Reaction Dynamics (GV)**

These lectures do not follow one specific text book or primer; however, the following books have all been used as source material and you may find some of them useful.

*Molecular Reaction Dynamics
- *R. D. Levine
Molecular Reaction Dynamics and Chemical Reactivity - R.D.Levine and
R.B. Berstein (previous version of above text by Levine)
Reaction Dynamics - M. Brouard
Atkins' Physical Chemistry - 8th Edition, p 885-894

*Chemical Kinetics and Reaction
Dynamics*, P. L. Houston (Dover)

**Lasers and Laser
Techniques (HHF)**

These lectures do not follow one specific text book or primer; however, the following books have all been used as source material and you may find some of them useful.

*Laser Chemistry, Wiley - H.
H. Telle, A. Gonzalez Urena and R. J. Donovan *
Laser Spectroscopy, 3. Ed., Springer - W. Demtröder
Molecular Quantum Mechanics, OUP - P. W. Atkins
and R. Friedman
Modern Spectroscopy, 4. Ed., Wiley - J. M. Holla

### Course Outline

**Photophysics and Photochemistry (9 lectures + 1 workshop) Dr Simon Banks **

This Module will introduce the following:

- interaction between light and matter.
- potential energy surfaces, electronic configurations and states.
- vibronic excitation, transition dipole moments and selection rules.
- fates of excited states: radiative and non-radiative processes, Jablonski and energy state diagrams.
- quantum yields; Stern-Volmer plots.
- Kasha’s rule; delayed fluorescence; excimer fluorescence.
- diabatic and adiabatic representations; Landau-Zener theory.
- deuterium isotope effect; conical intersections.
- singlet-triplet transitions – El Sayed’s rules.
- chemical change: dissociation; alkenes and carbonyls as exemplars of photochemical reactivity.

**Reaction Dynamics (9 lectures + 1 workshop)**

**Dr Giorgio Volpe**

This Module will introduce the following:

- Introduction & motivation
- Preliminaries (elementary versus complex processes, scattering and types of collisions)
- Useful definitions (including impact parameter, reaction cross-sections)
- Connection between impact parameter and scattering
- Microscopic understanding of chemical reaction rates and link to thermal rate constants
- Energy conservation
- Reference frames and Newton’s diagrams
- Reaction case studies (harpoon, sterically controlled reactions, long-lived intermediates)
- Potential energy surfaces, definition, measurement and calculation, trajectory calculations (early and late barriers)
- Experimental methods (molecular beams, reactant state selection, product state identification)
- Case studies/additional examples

**Lasers and Laser Techniques (9 lectures + problems in lecture) **

**Prof Helen Fielding**

This Module will introduce the following:

- Light-matter interactions: absorption, emission, polarisation, transition probabilities, spectral quantities, coherence, spectral line widths and profiles, homogeneous and inhomogeneous line broadening
- Theory of lasers: population inversion, threshold condition, resonators, properties of laser radiation, pulsed operation, mode locking, Q switching. Implementation of laser sources: solid-state lasers, gas lasers, dye lasers. Non-linear optical techniques: phase matching, second-harmonic generation, frequency mixing, high-harmonic generation
- Laser spectroscopy and laser chemistry: cavity ring-down spectroscopy, laser-induced fluorescence, REMPI, Doppler-free spectroscopy, laser photolysis, pump-probe experiments