12 settembre 2019

Physics of Sensors and Laboratory of Spectroscopy

Syllabus

 

1. Absorption and Emission of Light

1.1 Discrete and Continuous Absorption and Emission Spectra. 1.2 Transition Probabilities. 1.2.1 Lifetimes. Spontaneous and Radiationless Transitions. 1.2.2 Semiclassical Description. Basic Equations. 1.2.3 Weak-Field Approximation. 1.2.4 Transition Probabilities with Broad-band Excitation. 1.2.5 Phenomenological Inclusion of Decay Phenomena. 1.3 Problems.

 

2. Widths and Profiles of Spectral Lines

2.1 Natural Linewidth. 2.1.1 Lorentzian Line Profile of the Emitted Radiation. 2.1.2 Relation between Linewidth and Lifetime. 2.1.3 Natural Linewidth of Absorbing Transitions. 2.2 Doppler Width. 2.3 Collision Broadening of Spectral Lines. 2.3.1 Phenomenological Description. 2.3.2 Theoretical Treatment of Anelastic Collisions. 2.4 Saturation Broadening. 2.5 Problems.

 

3. Roto-Vibrational Spectroscopy

3.1 The Born-Oppenheimer Approximation. 3.2 Rotational Spectroscopy. 3.2.1. The rigid rotor. 3.2.2. Linear Rotor. Transition Frequencies. Selection Rules. Intensity. Centrifugal Distortion. 3.2.3. Symmetric Rotor Molecules. Prolate. Oblate. 3.2.4. Spherical Rotor Molecules. 3.2.5. Asymmetric Rotor Molecules.  3.3 Vibrational Spectroscopy. 3.3.1. The Harmonic Oscillator. 3.3.2. Infrared Spectra. 3.3.3. Electrical and Mechanical Anharmonicity. 3.4 Roto-Vibrational Spectroscopy. 3.4.1. P- R- and Q-branch. 3.4.2. Branches Asymmetry.  3.5 Polyatomic Molecules. 3.5.1. Normal modes of vibrations. 3.5.2. Group Vibrations. 3.6 Basics on HITRAN Database. 3.7 Example: Fundamental Band of Carbon Monoxide Molecule.

 

4. Spectroscopic Instrumentations

4.1 Spectrographs and Monochromators. Figures of Merit. 4.1.1. Speed of Spectrometer. 4.1.2. Spectral Transmission. 4.1.3. Spectral Resolving Power. 4.1.4. Free Spectral Range. 4.2 Prims Spectrometer. 4.3 Grating Spectrometer. 4.4 Interferometers. 4.4.1 Basic Concepts. 4.4.2 Michelson Interferometer. 4.4.3 Mach-Zehnder Interferometer. 4.4.4 Multiple-Beam Interference. 4.4.5 Fabry-Perot Interferometer. 4.4.6 Multilayer Dielectric Coatings. 4.5 Problems.

 

5. Doppler-Limited Absorption Laser Spectroscopic Techniques

5.1 Advantages of Laser Spectroscopy. 5.2 Direct Absorption Spectroscopy. 5.3 Modulation Techniques. 5.3.1 Amplitude Modulation. 5.3.2 Wavelength Modulation. 5.3.3 Lock-in detection. 5.4 Multipass Cell Absorption Spectroscopy. 5.4.1 White Multipass Cell. 5.4.2 Herriott Multipass Cell. 5.5 Cavity Enhanced Absorption Spectroscopy. 5.5.1 Longitudinal TEM00 cavity modes. 5.5.2 Finesse and spectral bandwidth. 5.5.3 Mode matching of the laser beam to the cavity. 5.5.4 Cavity Ring-Down Absorption spectroscopy. 5.6 Photoacoustic and Photothermal Spectroscopy. 5.6.1 Light absorption and heat generation. 5.6.2 Sound wave generation. 5.6.3. Thermal diffusion mode. 5.6.4. Detection of acoustic waves. 5.7 Quartz-enhanced photoacoustic spectroscopy. 5.7.1 Quartz tuning forks: flexural modes. 5.7.2 Pressure influence on damping and natural frequencies. 5.8 Comparison of different gas detection techniques. 5.8.1 Minimum absorption coefficient. 5.8.2 Normalized noise equivalent absorption. 5.9 Problem.

 

6. Physics of Sensors

6.1 Sensor Characteristics. 6.1.1 Transfer Function and Dynamic Range. 6.1.2 Accuracy. 6.1.3 Hysteresis. Saturation. Repeatability. Resolution. 6.1.4 Dynamic Characteristics. 6.1.5 Reliability. 6.1.6 Calibration of a gas sensor. 6.2 Physical Principles of Sensing. 6.2.1 Piezoelectric Effect. 6.2.2 Pyroelectric Effect. 6.2.3 Seebeck Effect. 6.2.4 Peltier Effect.

 

7. How to Prepare a Scientific Paper

7.1 Overview.  7.2 Structure and organization of a scientific paper. 7.2.1 Introduction. 7.2.2 Method. 7.2.3 Results and discussion. 7.2.4 Conclusions. 7.2.5 Abstract. 7.3 Scientific Style.  7.4 Basics on Data Analysis with OriginLab.

 

8. Laboratory Activities

8.1 Light-Current-Voltage Characterization of a Quantum Cascade Laser
8.2 Spectral Characterization of a Quantum Cascade Laser by using a FT-IR
8.3 Direct Absorption Spectroscopy
8.4 Wavelength Modulation Spectroscopy

 

TEXTBOOKS

W. Demtroder – Laser Spectroscopy – Basic Concepts and Instrumentation, Springer.
J. Fraden – Handbook of Modern Sensors – Physics Designs and Applications, Springer.

 

SLIDES

1. ABSORPTION AND EMISSION OF LIGHT

2. WIDTH AND PROFILE OF SPECTRAL LINES

3. ROTO-VIBRATIONAL SPECTROSCOPY

4. SPECTROSCOPIC INSTRUMENTATIONS

5. DOPPLER-LIMITED ABSORPTION LASER SPECTROSCOPIC TECHNIQUES

6. PHYSICS OF SENSORS

7. HOW TO PREPARE A SCIENTIFIC PAPER

 

Template for manuscript preparation with guidelines

Supplementary Files