"How does a photon get into an atom?" This question puzzled not only leading scientists, e.g. Schrödinger and Heisenberg. It is still asked by students. And it is, indeed, a key question of quantum mechanics.
James D. Macomber's book was the first to provide a didactic and unified approach to the answer. It has been updated with recent experimental results and modern theoretical interpretations, including quantum correlation effects in condensed matter, four-wave mixing and synchrotron radiation . The book has been written for final year undergraduate students in Chemistry and Physics. It provides an understanding for similarities among the spectroscopic methods, and is stimulating to read.