# Physical Chemistry

## Objectives

The UC aims to provide students with a relative in-depth knowledge and theoretical skills in optical spectroscopic methods, in particular:

1- Ability to predict electronic states in atoms and molecules and use simple quantum mechanical models such as the electron in a box and Huckel MO method to predict the energy of electronic transitions.

2- Ability to identify forbidden and allowed transitions between electronic states and coupling between electronic and vibrational states in molecules. To understand the features of molecular electronic spectra on the basis of the superposition of Franck-Condon factors.

3- To understand the selection rules and its fundamental basis of the interaction between electromagnetic radiation and transition dipole moments of molecules, and symmetry requirements for the initial and final state.

4-To use the harmonic oscillator model to predict the frequency of a particular vibration and rationalize the frequencies associated to functional groups in the IR spectrum. To understand the radiation-mater interaction mechanisms which are in the origin of infrared absorptions spectroscopy and Raman spectroscopy?

5-Master the practical aspects of the spectroscopies and the quantitative aspects related with the electronic transitions under study (molar absorptivity and quantum yield measurements).

## General characterization

##### Code

10696

##### Credits

6.0

##### Responsible teacher

Maria Madalena Alves de C.S.D. Andrade

##### Hours

Weekly - 3

Total - Available soon

##### Teaching language

Português

### Prerequisites

Available soon

### Bibliography

Available soon

### Teaching method

Available soon

### Evaluation method

Available soon

## Subject matter

**I. Electromagnetic radiation (general aspects)**

Electromagnetic radiation. Oscillating dipole as radiation generator. Radiation -matter interaction : refraction and Rayleigh scattering . Absorption and emission of light . Absorption of radiation to hydrogen. Bohr resonance condition . Spectroscopy and regions of the electromagnetic spectrum ; kind of transitions associated . Units and conversions in spectroscopy .

**II . Introduction to Quantum Chemistry**

Corpuscular and wave behaviour of light : interference and photoelectric effect . Interference effect for the electrons. Heisenberg Uncertainty Principle . Atomic orbitals . Wave function . General wave equation of classical mechanics . Schrödinger equation in one dimension .

**III . Molecular orbital theory**

Review diagram of molecular orbitals ( MOs ) for homonuclear diatomic molecules . Heteronuclear diatomic molecules . Analysis of the number of nodes. Classification of OMs as symmetry and parity . Molecular orbital diagram for heteroatomic molecules. Diagram of molecular orbitals for conjugated polyenes . Distinction between different transitions : σ - σ * , π - π * , n- π * , n- σ * , π - π * transitions and n- π * . Influence of polarity of the solvent. Blue and red shift.

Construction of OM diagrams for ML6 complexes: dd transitions . Electronic states and spectroscopic terms. Spectroscopy transition metals.

**IV. Equipment spectroscopy**

Radiation sources . Black body radiation. Rayleigh- Jeans and Planck Law. The Boltzmann distribution . Beam splitter . Dispersion equation for refractive index.

**V. Quantitative aspects of molecular absorption spectra of UV - Vis**

Transmittance , absorbance Lambert Law ; Derivation of Beer''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''s Law ; molar absorptivity . Limitations and deviations from the quantitative analysis .

Factors influencing the absorption intensity . Selection rules . Transitions allowed and forbidden transitions . Transition dipole moment. Oscillator strength .

Examples of UV-Vis spectra of proteins: different regions of the spectrum and its chromophore groups . Comparison with spectra collected in practical classes .

**VI . Vibrational spectra with resolution**

The harmonic oscillator . Morse curves . Franck - Condon principle . Jablonski diagrams . Multiplicity . Fluorescence and phosphorescence . New selection rules .

**VII . Vibrational Spectroscopy**

Infrared : Model Harmonic Oscillator vs Real anharmonic system. Definition of frequency of vibration, the force constant , k and reduced mass and its influence on the shape of the potential energy curve. The region where the IV characteristic bands appear functional groups . IR Spectroscopy Fourier Transform

Raman : elastic and inelastic scattering . Stokes and anti – Stokes scattering