98683 - LASERS

Learning outcomes

At the end of the course the student has acquired the basic principles of laser operation, knowledge of their optical properties and the chemical applications of the main commercially available laser sources.

Course contents

Principles of laser operation

• Stimulated emission
• Inversion of energy levels population
• Pumping processes
• Optical resonators
• The threshold condition in a real laser
• Continuous wave lasers
• Pulsed lasers
  
• Properties of laser's light
• Multi-mode and single-mode laser emission

Applications of laser light

• Uses of laser's light
• Raman spectroscopy

Commercially available lasers

The different types of laser sources and the physical or chemical phenomena which make them work.

• Atomic electronic emissions: He-Ne, Ar+ , and Nd3+ lasers
• Molecular vibronic: N2, excimer, and dye lasers
• Molecular rovibrational: CO2 and HF lasers
• Transition metals doped crystals: ruby and Ti:sapphire lasers
• Diode lasers

Instrumental techniques

• Non-linear optics for harmonics generation
• The creation of ultra short pulses
  - Q-switching
  - Mode-locking
  - Chirped pulse amplification

Laboratory laser-based experiments

• Photophysical characterization of ruby, a lasing material.
• Laser-induced fluorescence of gaseous molecular iodine
  
• Vibrational Raman spectroscopy of liquid and solid samples.
  
• Disentanglement of spectral properties of vegetable oils.

Quantum chemistry laboratory

• Calculation of the vibrational normal modes of simple molecules and simulation of the IR and Raman spectra.

Anonymous statistical survey

Once 2/3 of the lessons have been completed, a survey will be carried out to know students' opinions on the course, in order to make it more effective. Reference links:

• https://opinionistudenti.unibo.it
  
• https://val.unibo.it/ (student)
• https://val.unibo.it/demo.php (survey)
• https://gestioneval.unibo.it (lecturer)

Calendar - Theory (40 h, 13:30-15:30)

• 18/09/2024
  
• 19/09/2024
  
• 25/09/2024
  
• 26/09/2024
  
• 02/10/2024
  
• 03/10/2024
  
• 09/10/2024
  
• 10/10/2024 
  
• 16/10/2024 
  
• 17/10/2024 
  
• 23/10/2024 
  
• 24/10/2024 
  
• 30/10/2024 
  
• 31/10/2024 
  
• 06/11/2024 
• 07/11/2024
  
• 13/11/2024 
  
• 14/11/2024 
  
• 20/11/2024 
  
• 21/11/2024 
  

Calendar - Laboratory (20 h, 09:00-13:00)

• 27/11/2024 COMPUTATION (everybody)
  
• 02/12/2024 LASER - Shift A (groups 1,2,3,4)
  
• 03/12/2024 LASER - Shift B (groups 5,6,7,8,9)
  
• 04/12/2024 LASER - Shift A (groups 1,2,3,4)
• 05/12/2024 LASER - Shift B (groups 5,6,7,8,9)
  
• 09/12/2024 LASER - Shift A (groups 1,2,3,4)
• 10/12/2024 LASER - Shift B (groups 5,6,7,8,9)
  
• 11/12/2024 DATA ANALYSIS AND REPORT DELIVERY (everybody)
  

Readings/Bibliography

• David L. Andrews
  Lasers in Chemistry
  Springer, 3rd edition

• Orazio Svelto
  Principles of Lasers
  Plenum Press, 4th edition

• Donald A. McQuarrie & John D. Simon
  Physical Chemistry: A Molecular Approach
  University Science Book
  - Chapter 15: Lasers, Laser Spectroscopy, and Photochemistry
  - Chapter 12: Group Theory: The Exploitation of Symmetry

 

Teaching methods

Projector for transparencies and slides in the classroom.

Laser instrumentation available in the laboratory for Laser-based experiments.

• Vacuum line + Thermostat + Spectrometer Ocean-HR + DPSS laser (green 532 nm)
  LIF I2
• Spectrometer Ocean USB4000 + DPSS and diode lasers (red, 671 nm)
  Spectral features of vegetable oils
  
• Spectrophotometer + Spectrofluorometer
  Photophysical characterization of Ruby
  
• Raman spectrometer Ventana 532 nm + DPSS laser (green)
  Raman Stokes spectroscopy of liquid and solid materials
  
• Spectrofluorometer + DPSS laser (blue 473 nm)
  Raman Stokes and anti-Stokes spectroscopy of liquids

As concerns the teaching methods of this course unit, all students must attend Module 1, 2 [https://www.unibo.it/en/services-and-opportunities/health-and-assistance/health-and-safety/online-course-on-health-and-safety-in-study-and-internship-areas] online, while Module 3 on health and safety is to be attended in class or on Microsoft Teams according to the modality chosen by the teacher. Information about Module 3 attendance schedule is available on the website of your degree programme.

Assessment methods

The assessment for the LASERS module is a single oral exam at the end of the semester (upon request it is possible to fix an additional date before Christmas).

The student has to report on three topics of the educational program, including:

• principle and properties of lasers
• laser sources
• laboratory activity (the reports can be used during the examination)
  

The duration of the exam is approximately 30 minutes.

The exam can be passed with a minimum score of 18/30.

The grade for the entire APPLIED PHYSICAL CHEMISTRY integrate course is calculated as the average of the grades obtained in the two modules (if both are at least 18/30).

Teaching tools

Lessons in the classroom (4 CFU) for the theory, numerical exercises in the classroom or in the laboratory (1 CFU), and laboratory activities (1 CFU) where lasers-based experiments are performed.

Lecture notes are available in electronic format on the course's institutional website:

Students who need compensatory tools because of disabilities or specific learning disorders (SLD) can contact:

• https://site.unibo.it/studenti-con-disabilita-e-dsa/en

to agree on the adoption of the most appropriate measures.

Office hours

See the website of Assimo Maris