Molecular Vibrational Rotational Spectra

This work had its beginnings in the early 1980s at the University ofWollongong, with significant contributions from Dr. Margret Hamilton, Professors Peter G. Burton and Greg Doherty. The emphasis was to develop computer code to solve the nuclear Schrodinger problem. For bent triatomic molecules the project was fmally realized at the University of Newcastle a decade or so later, with the contribution from Ms. Feng Wan g. Aspects of this work are now taught in the quantum mechanics and electron spectroscopy courses at The University of Newcastle. Even now "complete" ab initio solutions of the time-independent SchrOdinger equation is not commonplace for molecules containing four atoms or more. In fact, when using the Eckart-Watson nuclear Hamiltonian a further restriction needs to be imposed; that is, the molecule is restricted to undergoing small amplitudes of vibration. This Hamiltonian is useful for molecules containing massive nuclei and moreover, has been extremely useful in interpreting the rovibrational spectra of small molecules. Nevertheless, a number of nuclear Hamiltonians that do not embed an equilibrium geometry have become well established and are extremely successful in interpreting rovibrational spectra of floppy molecules. Furthermore, solution algorithms vary greatly from research group to research group and it is still unclear which aspects will survive the next decade. For example, even for a triatomic molecule a general form of a potential function has not yet been uncovered that will generally interpolate with accuracy and precision ab initio discrete surfaces.

The definitive text on the rotational spectroscopy of diatomic molecules.

The book reviews the results of vibration-rotational spectroscopy of molecules obtained recently by combining modern computational methods of quantum chemistry with the new techniques of high-resolution rotational and vibration-rotational spectroscopy. It shows for example that the tunneling vibration-rotational spectroscopy of the van der Waals complexes provides a new look at intermolecular forces while the high precision and sensitivity of the submillimeter-wave and Fourier transform microwave spectroscopy make it possible to study complex rotational spectra of molecules in excited vibrational states. New results of high level ab initio quantum chemical computations of vibrational and rotational energy levels and dipole moment functions of unusual molecules will be discussed together with the recent discovery of clustering of energy levels in asymmetric tops. Group theoretical analysis of floppy molecules, especially the tunneling effects in nonrigid molecules, will also be discussed. Contents:High-Resolution Spectroscopy of Transient Molecules and Its Applications to Molecular Dynamics (E Hirota & Y Endo)Vibration-Rotation Spectra of Reactive Molecules: Interplay of Ab Initio Calculations and High-Resolution Experimental Studies (H Bürger & W Thiel)Rotational Spectra of Symmetric Top Molecules: Correlation-Free Reduced Forms of Hamiltonians, Advances in Measuring Techniques, and Determination of Molecular Parameters from Experimental Data (K Sarka et al.)Hot Bands in Infrared Spectra of Symmetric Top and Some Other Molecules. A Useful Tool to Reach Hidden Information (G Graner & H Bürger)The Formation of Four-Fold Rovibrational Energy Clusters in H2S, H2Se, and H2Te (P Jensen et al.)Phase Angles in the Matrix Elements of Molecular Spectroscopy (C di Lauro & F Lattanzi)High-Resolution Infrared Spectroscopy and One-Dimensional Large Amplitude Motion in Asymmetric Tops: HNO3 and H2O2 (J-M Flaud & A Perrin)Extended Molecular Symmetry Groups: Symmetry Analysis of Molecules Consisting of Two Coaxial Rotors (P Soldán)Quantum-Mechanical Studies of Radiative Association Reactions: Formation of HeH+, NeH+ and ArH+ (W P Kraemer et al.) Readership: Chemists, astrophysicists, laser physicists and other general physicists. keywords:Transient and Reactive Molecules;Reduced Hamiltonians;Hot Bands;Rovibrational Energy Clusters;Phase Angles in Matrix Elements;Large Amplitude Vibrations;Molecular Symmetry Groups;Radiation Association Reactions

The book reviews the results of vibration-rotational spectroscopy of molecules obtained recently by combining modern computational methods of quantum chemistry with the new techniques of high-resolution rotational and vibration-rotational spectroscopy. It shows for example that the tunneling vibration-rotational spectroscopy of the van der Waals complexes provides a new look at intermolecular forces while the high precision and sensitivity of the submillimeter-wave and Fourier transform microwave spectroscopy make it possible to study complex rotational spectra of molecules in excited vibrational states. New results of high level ab initio quantum chemical computations of vibrational and rotational energy levels and dipole moment functions of unusual molecules will be discussed together with the recent discovery of clustering of energy levels in asymmetric tops. Group theoretical analysis of floppy molecules, especially the tunneling effects in nonrigid molecules, will also be discussed.

Physical Chemistry, A Series of Monographs: Rotational Spectra and Molecular Structure covers the energy levels and rotational transitions. This book is divided into nine chapters that evaluate the rigid asymmetric top molecules and the nuclear spin statistics for asymmetric tops. Some of the topics covered in the book are the asymmetric rotor functions; rotational transition intensities; classes of molecules; nuclear spin statistics for linear molecules and symmetric tops; and classical appearance of centrifugal and coriolis forces. Other chapters deal with the energy levels and effects of centrifugal distortion, as well as the internuclear distance and moments of inertia. The discussion then shifts to the coriolis coupling effects on rotational constants and the perturbation treatment of vibration-rotational Hamiltonian. The last chapter is devoted to the examination of origin of the quadrupole interaction. The book can provide useful information to chemists, physicists, electrical engineers, students, and researchers.