
I am most pleased and, in a way, I feel honored to write the Foreword for the book The Hanle Effect and Level-Crossing Spectroscopy, which covers such a very wide range of applications not only in the initial areas of atomic and molecular physics, but also in solid state physics,...

1 The Hanle Effect and Level-Crossing Spectroscopy-An Introduction.- 1. Historical Survey.- 2. Classical Interpretation of the Hanle Effect.- 3. Quantum Mechanical Interpretation of the Hanle Effect.- 4. The Density Matrix Formalism for the Hanle Effect (Broad-Band Excitation).-...