[...]... them The development of quantum physics in the first three decades of the twentieth century went hand in hand with the understanding of atomic structure and of the coupling of atoms to the electromagnetic field This chapter will consider energy levels, particularly discrete, in hydrogen as well as in heavier atoms and positive ions, and techniques for calculating them and of the transitions between... considers the effect of electric and magnetic fields on this phenomenon, of importance both in the laboratory and in astrophysical plasmas Chapter 6 deals with molecular s t r u c t u r e and spectra, particularly of simple diatomic molecules, which serve to introduce the basic elements of molecular physics The final Chapter 7 extends to larger molecules and to the variety of molecular interactions that... consultation and, therefore, are heavily weighted to review articles and textbooks Most of our knowledge and understanding come from such sources and this is an appropriate place to indicate my indebtedness Much of the quantum mechanics I have learnt is from L D Landau and E M Lifshitz, Quantum Mechanics: Non-relativistic theory (Pergamon, Oxford, 1977) I have learnt most of what I know of molecular physics. .. kind, and has become of the highest importance for all branches of natural science It has excited the admiration and stimulated the fancy of men as hardly any other discovery has done, because it has permitted an insight into worlds that 1 2 ASTRONOMY-INSPIRED ATOMIC AND MOLECULAR PHYSICS seemed forever veiled to us.” (F Cajori: A History of Physics (MacMillan, N.Y., 1899), p 160) Spectroscopy gave a handle... orbital and spin wave functions as in (1.22) no longer holds but these expressions point to the required extension By specifying both orbital and spin labels for each orbital, each of the four terms in (1.22) can be cast in the form of 2 × 2 determinants Thus, the singlet state in (1.22) can be written as 22 ASTRONOMY-INSPIRED ATOMIC AND MOLECULAR PHYSICS where the 1 and 2 within parentheses stand for...x ASTRONOMY-INSPIRED ATOMIC AND MOLECULAR PHYSICS chapter ends with problems suited for homework assignments They are of two types, some to work out derivations only sketched in the text, and others to illustrate applications of results Chapter 1 considers the early beginnings of a modern, scientific study of the astronomical Universe, when spectra from the Sun and other stars provided the first handle... the time-independent Schrödinger equation, with the one-electron Hamiltonian 4 ASTRONOMY-INSPIRED ATOMIC AND MOLECULAR PHYSICS Here is the reduced mass of (electron+nucleus): and where we have generalized (1.2) to an arbitrary charge Z for the nucleus which proves convenient for handling other hydrogen-like positive ions and atoms heavier than hydrogen The spherical symmetry of the Coulomb potential... important and the attendant spin-orbit interactions that couple S and L become appreciable, are such “inter-combination” transitions between states of different S seen, the notable example being the spectrum of Hg, its familiar blue lines arising from 16 3.3 ASTRONOMY-INSPIRED ATOMIC AND MOLECULAR PHYSICS Configuration interaction The two-electron Hamiltonian in (1.17) being non-separable in and the... have smaller radial extent and lie below the “surface” of the atom This is first manifest in the transition elements where, once and shells are filled, with 18 electrons in the noble gas Ar, the next two electrons fill rather 18 ASTRONOMY-INSPIRED ATOMIC AND MOLECULAR PHYSICS than The dominant ground state configuration of Ca(20) is, therefore, After this, the is occupied and then the (same the taking... empirical set of numbers is and 4.2 for Together, such a model of screening (inner and outer) and core penetration leads to a description of the energy for any orbital and a corresponding wave function which, for example, in B would be again with each factor involving its own and Although a relatively simple approximation based on classical physics and ignoring antisymmetrization and attendant exchange . nuclear spin 3 Molecular Spectra 3.1 3.2 3.3 3.4 Rotational spectra Vibrational spectra Raman spectra Electronic spectra viii ASTRONOMY-INSPIRED ATOMIC AND MOLECULAR PHYSICS 3.5 3.6 External field. of Cambridge, U.K. ASTRONOMY-INSPIRED ATOMIC AND MOLECULAR PHYSICS by A. R. P. RAU Department of Physics and Astronomy, Louisiana State University, Baton Rouge, U.S .A. KLUWER ACADEMIC PUBLISHERS NEW.