Springer Chemical Physics

1. Introduction.- 1.1 Historical Background of Free Radical Studies by High-Resolution Spectroscopy.- 1.2 Significance of High-Resolution Spectra of Transient Molecules.- 2. Theoretical Aspects of High-Resolution Molecular Spectra.- 2.1 Molecular Rotation.- 2.1.1 Angular Momentum.- 2.1.2 Rotational Energy of a Rigid Body.- 2.2 Vibration-Rotation Interaction.- 2.3 Fine and Hyperfine Structures.- 2.3.1 Electron Spin and Electron Orbital Angular Momenta.- 2.3.2 Fine-Structure Hamiltonian.- 2.3.3 Hamiltonian Matrix Elements Appropriate for Hund's Case (a).- 2.3.4 ?-Type Doubling in 2? States.- 2.3.5 Hamiltonian Matrix Elements Appropriate for Hund's Case (b).- 2.3.6 Rotational Structure of a 2E Molecule.- 2.3.7 Hyperfine Interaction.- 2.3.8 Matrix Elements of the Hyperfine Interaction Appropriate for Case (a)?.- 2.3.9 Matrix Elements of the Hyperfine Interaction Appropriate for Case (b)?J.- 2.3.10 Hyperfine Interactions Caused by More than One Nucleus.- 2.3.11 Hyperfine Interactions in a C3v Symmetric Top Molecule.- 2.4 Vibronic Interaction Including the Renner-Teller Effect.- 2.4.1 Born-Oppenheimer Approximation and Vibronic Interaction.- 2.4.2 Renner Effect on a Linear Polyatomic Molecule in a ? Electronic State.- 2.4.3 Rotational Energy Levels of a Linear Triatomic Molecule Affected by Vibronic Interactions.- 2.4.4 Hyperfine Structure in a 2? Polyatomic Molecule Affected by Rovibronic Interactions.- 2.5 Zeeman and Stark Effects.- 2.5.1 Zeeman Effect of a Molecule Without Orbital Angular Momentum.- 2.5.2 Zeeman Effect of a Molecule with Electron Orbital Angular Momentum.- 2.5.3 Stark Effect.- 3. Experimental Details.- 3.1 Microwave Spectrometer.- 3.1.1 Requirements to be Met by a Microwave Spectrometer for the Study of Transient Molecules.- 3.1.2 Historical Survey of Microwave Studies of Transient Molecules.- 3.1.3 High Sensitivity Millimeter-Wave Spectrometer to Study Transient Molecules.- 3.2 Infrared Laser Spectrometers.- 3.2.1 Diode Laser Spectrometer.- 3.2.2 Infrared Laser Magnetic Resonance Spectrometer.- 3.2.3 Far-Infrared Laser Magnetic Resonance Spectrometer.- 3.2.4 Difference Frequency Laser Spectrometer.- 3.3 Dye Laser Spectroscopic System.- 3.3.1 CW Dye Laser.- 3.3.2 Doppler-Limited Excitation Spectroscopy Using a CW Dye Laser as a Source.- 3.3.3 Intermodulated Fluorescence Spectroscopy.- 3.4 Double Resonance Spectroscopy.- 3.4.1 Microwave or Radio Frequency Optical Double Resonance.- 3.4.2 An MODR Spectrometer to Study Transient Molecules.- 3.4.3 Infrared-Optical Double Resonance.- 3.5 Generation of Transient Molecules.- 4. Individual Molecules.- 4.1 Diatomic Free Radicals.- 4.1.1 2? and 3? Diatomic Molecules.- 4.1.2 2? Diatomic Molecules.- 4.1.3 Molecules in ? States.- 4.2 Linear Polyatomic Molecules.- 4.2.1 Molecules in ? Electronic States.- 4.2.2 Molecules in ? Electronic States.- 4.3 Nonlinear XY2- and XYZ-Type Triatomic Free Radicals.- 4.3.1 Nonlinear XYZ-Type Free Radicals of Cs Symmetry.- 4.3.2 Nonlinear XY2 -Type Free Radicals of C2v Symmetry.- 4.3.3 Molecular Structure and Anharmonic Potential Constants of Nonlinear XYZ-Type Molecules of Cs Symmetry.- 4.4 Symmetric Top and Other Polyatomic Free Radicals.- 4.4.1 The Methyl Radical CH3.- 4.4.2 The Trifluoromethyl Radical CF3.- 4.4.3 Structures and Internal Motions of the Methyl Radical and Its Derivatives.- 4.4.4 The NO3 Radical.- 4.4.5 The Methoxy Radical CH3O.- 4.5 Fine and Hyperfme Interactions in Free Radicals.- 4.5.1 Hyperfme Interaction Constants of Diatomic Molecules.- 4.5.2 Spin-Rotation Interaction in Nonlinear Polyatomic Molecules.- 4.5.3 Hyperfme Interaction in Nonlinear Polyatomic Molecules.- 4.6 Molecules in Metastable Electronic States.- 4.6.1 LEF and MODR Study of H2CS in the a3A2 State.- 4.6.2 Perturbations in the Singlet-Singlet Transition of a Few Simple Carbenes.- 5. Applications and Future Prospects.- 5.1 Applications to Chemical Reactions.- 5.2 Applications to Atmospheric Chemistry.- 5.3 Applications to Astronomy.- 5.3.1 HCCN.- 5.3.2 Phosphorus-Containing Compounds.- 5.4 Future Developments.- 5.4.1 Possible Improvements of Spectroscopic Techniques.- 5.4.2 Future Trends in High-Resolution Spectroscopic Studies of Transient Molecules.- References.