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Lasers and their applications in chemistry. Dr Dean Venables (G16). Course outline. Part (1) looks at what lasers are and how they work . What is a laser? What are its properties? How does a laser work? What molecular transitions produce laser operation?
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Lasers and their applications in chemistry Dr Dean Venables (G16)
Course outline Part (1) looks at what lasers are and how they work What is a laser? What are its properties? How does a laser work? What molecular transitions produce laser operation? How are these practically realised? What are some common types of laser? Part (2) looks at several applications of lasers in chemistry Laser spectroscopy 1 test and 1 assignment
References • Basic overview of lasers: • Atkins, de Paula, Physical Chemistry • Hollas, Modern Spectroscopy • More advanced texts on lasers and their applications: • Milonni, Eberly, Lasers • Siegman, Lasers • Silfast, Laser Fundamentals • Telle, Urena, Donovan, Laser Chemistry: Spectroscopy, Dynamics, and Applications • Demtröder, Laser Spectroscopy: Basic Concepts and Instrumentation (These are all available in the library)
1.1 Lasers – an introduction What is a laser? “LASER”: Light Amplification by the Stimulated Emission of Radiation “A laser is a device that amplifies light and produces a highly directional, high intensity beam that most often has a very pure frequency or wavelength” [Silfast]
Lasers have unique characteristics as light sources: Directionality Monochromaticity Brightness Coherence Other properties: Pulsed or continuous operation Tunable Polarised light
Why are these properties useful? Video: Applications of lasers
Principal components of a laser 1. Gain medium2. Laser pumping energy3. High reflector4. Output coupler5. Laser beam
Preconditions for laser operation “Population inversion” - consider populations of and transitions between energy levels in molecules in the gain medium (1) Optical cavity - look at the physical design of a laser – cavity formed by the high reflector (3) and output coupler (4) 1. Gain medium2. Laser pumping energy3. High reflector4. Output coupler5. Laser beam
A short sketch of laser history 1917: Einstein – stimulated absorption and emission of light 1954: Charles Townes and Schawlow – maser, prediction of the optical laser Nobel Prize (1964) 1960: Theodore Maiman – first demonstration of a laser: Ruby laser Rapid progress in the 1960s: 1961: first gas laser, first Nd laser 1962: first semiconductor laser 1963: CO2 laser (IR)