Modern Atomic Physics

Atomic spectroscopy heralded early quantum concepts at the turn of the last century. Whether it was Niels Bohr's atomic model motivated by the need to explain the discrete nature of atomic spectral lines in the solar spectrum or discharge tubes, or radiative processes in atoms, through Einstein's A and B coefficients, these were all leaps in scientific thought that led to newer ways of looking at nature through the eyes of quantum mechanics. Thus, atomic physics and atomic spectroscopy played the 'lead role' in unravelling the physical world at the sub-microscopic scale. With later developments in nuclear physics, high energy physics and subsequently the semiconductor revolution, atomic physics and pure atomic spectroscopy was all but forgotten as a branch of physics that yielded fundamental advances. Until the invention of the laser in 1960.